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July 2024

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World Premiere Review!
Backert Labs Rhumba Extreme 1.4 Preamplifier Review
An outstanding preamplifier with excellent connectivity for the music lover who desires more.
Review By Rick Becker


Backert Labs Rhumba Extreme 1.4 Preamplifier Review


   Backert Labs has seemingly come out of nowhere. Their first review appeared in 2015 and Enjoy the Music.com reviewed the 1.3 version of the Rhumba Extreme in 2019. This micro-manufacturer specializes in tube-powered preamplifiers, with a tube phono stage being a logical extension of their focus. All of their manufacturing and assembly is done in the USA. I had heard the buzz on the brand only one other time before my audio buddy, Tom, informed me that he had ordered a Rhumba 1.2 on US Audiomart that had been upgraded to a 1.3. Listening to his familiar system, I noticed an impressive improvement. When the 1.4 series was announced I contacted Andy Tebbe, the President and frontman of the company, and was promised a premiere review when the design was finalized.

I waited, and waited, until finally, I met Andy at the Capital Audiofest. He explained that Bob Backert, the designer and CEO of this company kept coming up with incremental improvements that slowed final release. I can understand that kind of addiction to perfection – not that my reviews are perfect, but I hate to realize there was something else I should have checked out or tested after a review is published. It has to be even more difficult for Bob as his name is on the product. Furthermore, being a small business, he has chosen to focus on preamps rather than expand the product line to become all things to all people like many major players (and many smaller ones.) He's kind of like the placekicker in football who does one thing extremely well and ends up being the top scorer (or close to it) at the end of the season.

While specialization has been a road to success for Backert Labs, it makes it challenging to promote the brand at shows. Most rooms you visit will have both the preamp and power amp from that same manufacturer on active display, as well as additional products. Last November the Dr. Vinyl room (709) at Capital Audiofest featured a rig cobbled together from the numerous quality brands this retailer sells. That Dr. Vinyl chose to display the Backert preamp is an enthusiastic endorsement. However, with so many different brands in the system, it becomes difficult to ascertain the strengths and weaknesses of individual components. It can take a lot of repetitive exposure to sort out the contribution and quality of a brand solely by attending shows. Having the product at home for review among familiar products takes that process to the next level, though it is not as definitive as trying it out in your own system. For that, a 14-day home trial period is offered when you purchase the preamp.

The Rhumba Extreme appealed to me for several reasons, not the least of which is I'm "Old School". With the advent and popularity of streaming, the preamplifier category has become increasingly blurred and even challenged by the resurgence of "all-in-one" units. The idea of including a DAC, streamer, and even a phono stage such as the AGD Andante preamplifier that I reviewed in 2020, can be appealing when space is limited or when you factor in the cost of expensive interconnects and power cords. (And I'm of the belief that you should not short-change your system by going ‘cheap' on either of those – power cords in particular.)


The Form Factor
Backert Labs essentially makes a good / better / best version using the same form factor and upgrading the technology as you progress up their line. I selected the Rhumba Extreme 1.4 ($8500) because it was said to have a lot of the best technology from the flagship Rhythm line stage ($12,900) in a less expensive chassis. It was also a step up in price from the Coincident Statement Line Stage that I have been using since 2010, but with a little stretch, still was within my comfort zone. The higher an electrical component gets above a five-figure price, the more I lose interest, speakers being an exception. Your pockets may be deeper than mine, which is fine, but I encourage people not to spend above their means. It makes it more difficult to enjoy the music if you've over-spent on the cost of admission. And besides, a little bit of savvy tweaking can help the tortoise outperform the hare.

The Rhumba Extreme has a front panel similar to the CAT SL1 preamp I owned before the Coincident. Center knobs are flanked by horizontal slots containing additional controls with vertical toggle switches. Unlike the Coincident and current CAT preamps, the Backert uses a single volume control with a separate knob for balance and a knob for source selection.



On the far left is a switch for mute/listen with a red LED light next to it that reminds you when you are muted. I found this light to be a very handy reminder. The informative owner's manual suggests it can be used, for example, when cueing an LP to avoid a "thump" upon stylus contact. Not doing so permitted only a very slight sound when the stylus reached the vinyl, although this may have been more a function of the gentle cueing feature of the tonearm than the preamp. When selecting a new source there was silence when the knob settled smoothly into the detents. (I only used three of the five inputs.)

With the silver faceplate, the lettering and numbering of the controls on the faceplate are on the faint side of readable unless you are facing it straight-on in decent light. I like to listen in the dark or low light and the preamp was positioned on a lower shelf on the rack, so this was a bit inconvenient at first. With careful sequencing of the inputs and more familiarity, this became less of an issue. The black faceplate with white lettering should be more readable.

The red light for mute also comes on when you first fire up the Rhumba as the unit is automatically silenced for about 40 seconds to avoid being blasted by music and to improve the longevity of the tubes by giving them a chance to warm up before music comes to life. I didn't notice a major improvement in sound quality with long warm-ups. The music was enjoyable from the start – so much so that I frequently had to consciously force myself back into critical listening mode to stay on task.


Mono A Mano
Next to the red light is a mono/stereo switch that came in handy with some of my early Dylan LPs. The mono versions were a buck cheaper than the stereo LPs and I was grateful to have even a mono rig back then. I spent an afternoon playing mono LPs in three different modes: first, with the switch in the stereo position, second, with the switch in mono, and third, with the switch in mono and the balance knob full to the right speaker. Listening to monaural LPs through a single speaker had a nostalgic righteousness, but the music didn't get out of the box. Listening in stereo mode with both speakers, the music simulated a spaciousness with a broad image between the speakers, as you probably know, but the instrumental images didn't congeal.

Listening to monaural LPs in mono mode through both speakers solidified the music between the speakers and was the most enjoyable in the long run. This listening was all done with my Charisma Audio Reference One stereo MC cartridge with a super-fine-line stylus. I should update my review of this cartridge as the system currently in place shows it to be much better than originally rated. And I should also repeat this monaural exercise with a true mono cartridge. A project for another day.

Monaural LPs for this exercise included:

Bob Dylan, (Self-titled)

Buddy Holly, The Buddy Holly Story

Elvis Presley, (Self-titled)

Berlioz Symphonie Fantastique, Orchestre National de la RadiodiffusionFrancaise

Glen Miller, RCA Collectors Issue, Second Pressing

Louis Armstrong and His Hot Five, The Louis Armstrong Story, Vol. 1

Stuff I'm sure you're all familiar with....


Most interesting in this exercise was that the Buddy Holly and Elvis Presley LPs had been treated with SoundGuard in the early 1970s and had been played innumerable times, yet they were completely free of clicks-and-pops! I felt like I was listening to $35 remasters, except the inner detail wasn't quite as fine. I'll have to ask Charles Kirmuss about that.



Moving further to the right is the source selector knob for the five inputs (#1 and #2 are balanced XLR; #3, #4, and #5 are RCA). This gives me an open RCA input after I've connected my tuner and Coincident Statement Phono Stage. The LampizatOr DAC was initially used in a balanced input, but I'll get back to that later. A slice of colored tape on the knob and a triangle, circle, and square piece of tape above each of my active inputs will facilitate source selection in low light for my kindergarten brain. Actually, clustering the sources in inputs #2, 3, and 4 helped out a lot.



The large knob in the center is obviously the volume control – the main function of a preamplifier, and it has a bright blue LED that is easily visible across a long room to give you an indication of where the volume is set. The volume and mute functions are also controlled by an elegant remote control that must be in the line of sight with the sensor in the slot on the right. The remote also has a blue LED that flashes when pressing the up, down or mute buttons. The remote lacks tacky synthetic feet like on the LampizatOr remote which keeps that from sliding off the leather arm of my recliner. Yes, that's a first-world problem, for sure. (Search: "clear silicone rubber feet" for a solution.) A pair of AAA batteries slide into the end of the remote after removing the chrome cap with a 1.5mm Allen wrench when it comes time to replace them. I recommend doing this on a dishcloth on a kitchen counter so you don't lose the tiny screws in the foreboding mechanism of your recliner.



On top of the Backert preamps is the portal for the two 12AU7 vacuum tubes (or equivalent.) The faint glow of the two tubes is visible in the dark through the clear cover made of scratch and heat-resistant polycarbonate. It is held in place with two embedded magnets, making for easy removal for tube rolling. (More on that later.) This arrangement also makes a flat profile that facilitates placing the unit into a rack.



On the bottom, three IsoAcoustics Gaia footers are attached to a large brass plate that is itself attached to the bottom. The brass plate adds mass and is said to enhance the sound of the preamp. This design has to be far better than typical inexpensive rubber or Sorbothane feet and it is one of the trickle-down features from the flagship Rhythm preamp. As good as the Gaia footers may be, I found adding three Stack Audio Auva EQ1 footers ($185, including shipping) was a significant and high-value upgrade among the several footers I tried.

The Gaia provided a little better stability in that they were anchored to the chassis, but Auva EQ1 lowered the noise even further and improved resolution. The weight of the Rhumba Extreme (24.4 pounds) kept the preamp stable with both footers, but it was necessary to bolster the preamp from the front when inserting tight-fitting interconnects.



Moving around to the back of the preamp there is an ample selection of inputs and outputs – a veritable reviewer's dream! (Actually, my big dream is to have a rack that isn't tight against the wall to facilitate the endless cable swapping that goes along with this sport.) On the right side (facing) are the two sets of balanced inputs and three sets of single-ended inputs I've already mentioned. The extra RCA input kept beckoning me to connect my vintage Technics cassette player. Those are true balanced inputs (and outputs) on all Backert components. Next, there is a Record output (RCA) that can be used to connect a headphone amplifier, and a Theater Bypass (RCA) for those with even more complex systems.  (The Theater Bypass works when the preamp is turned off, so you do not run your tubes when watching movies.

Also, both balanced XLR and unbalanced RCA outputs remain active in Theater mode if you are using multiple power amps to drive your main speakers.) The outputs include two sets of RCA and two sets of XLR balanced outputs which will be welcomed by those who are into bi-amp'ing or with dual subwoofers. Unlike the Coincident line stage, you can use any combination of the RCA and XLR outputs, so you could both bi-amp your main speakers and still have outputs for your subwoofers.

Further over to the left is a Furutech IEC inlet with a fuse drawer to make swapping fuses relatively easy. The Rhumba Extreme takes a 1A Fast-blo, small (5mm x 20mm) fuse. I'm currently using Synergistic Research Master fuses in my DAC and phono stage, and the new Pink fuse in both my monoblock tube amps and the AGD Audion monoblocks. There is also a Pink fuse in my hot-rodded Sony ES CD player (used as a transport). The hot-rodded Sony ES tuner has no fuse. A full review of the Pink fuse and Synergistic Research's new PowerCell8 SX will follow shortly. Unfortunately, I didn't have a Pink fuse on hand for the Rhumba but I expect it would take it to an even higher level of musicality.

Near the IEC inlet is what looked like a binding post for use with external grounding systems that have become a more important category over the past five years or so. Do not loosen this as it holds the power transformer in place and you will not be able to re-tighten it. It probably should have a warning sticker placed next to it. To ground the chassis you can use a screw on the bottom of the chassis. They have masked off one screw hole at the back corner before painting to allow direct contact with the metal. Masking off the screws on both back corners would offer even more flexibility.


The Preamp Blog
On the website you will find an interesting and informative primer called The Preamp Blog in which they discuss everything most audiophiles want to know about preamps, from tubes to impedance to power cords and fuses. They even delve into "What's the best-sounding Beatles song?" It gave me a lot of insight into the vision, expertise, and values of this relatively new company which encouraged me to seek out a review sample at the start of this adventure. My time and your time will be better spent by exploring this well-written blog yourself, rather than me trying to distill it.



So, What's a "GreenForce"?
After working with the heavy CAT and Convergent preamps with their heavy external power supplies, I was a bit skeptical about the Backert, at first. Common wisdom says bigger, external power supplies are better, yet the Backert Labs preamps are all single chassis and relatively light with their aluminum housing. They also feature the GreenForce power supply for which Bob Backert received a patent in 2013. The Rhumba Extreme comes with dual-mono power supplies and regulators and it seems to be something quite special, resulting in a relatively lightweight product.

There is an excellent description of this novel power supply on their website for those who want a detailed explanation. As a teaser, it states: Unlike traditional power supplies, in which a capacitor passively bleeds power out when the amplifier needs it, GreenForce provides power to the amplifier at all times with a kind of pressure, or force, that makes GreenForce proactive rather than passive.

Basically, it operates kind of like a Class A power amp that supplies full power all the time and the music signal draws from it as needed. Except it has less than 1.5uF (microfarads) of capacitance, rather than anywhere from 200uF to thousands of uF like traditional linear power supplies. Working with such small-value capacitors allows Backert Labs to use expensive, very high-quality polypropylene capacitors rather than the much higher capacitance electrolytic capacitors used in most linear power supplies. The much smaller value capacitors translate into much less hazardous waste in the long run, hence the "Green" in GreenForce.

Operationally, the very low output impedance of the GreenForce circuitry (less than 75 Ohms) allows the Backert Labs preamps to be used with virtually any amplifier. And the use of such high-quality capacitors leads to sound quality that... well, read on.



Beauty Is In The Ear Of The Beholder
From the moment I took it out of the box, it was clear the Rhumba Extreme 1.4 preamp is a well-thought-out and designed component with excellent build quality. There are no visible screws or ventilation slots on the chassis itself, giving it a very clean look. It is designed for the person who has or expects to evolve into owning a fairly extensive high-end system. It has flexible connectivity without locking in a phono stage, DAC, or streamer that may be unnecessary for your needs or become technologically obsolete. It is a Class A design with auto-bias, zero negative feedback, and low current and voltage passing through the tubes which coincidentally embodies long and trouble-free tube life.

The priority at Backert Labs has always been sound quality. So, while it doesn't engender the love I have for the unique visual forms of my Charisma Audio turntable, Coincident Statement Line Stage, or AGD monoblocks with polished finish, the appeal of the Rhumba Extreme is the music that flows through it.

If you've read my previous review of the Acora QRC-2 speakers, you know I initially felt some misgivings about its performance in the bass and top end. Adding the Rhumba Extreme corrected those shortcomings and made the music even more addicting. The bass tightened up, the timbre improved and the speaker dug deeper into its 29Hz published limit. At the top end, the Acora lacked the resolution and air that I knew Acora speakers were capable of from the many times I've heard and awarded them at shows. The Rhumba Extreme addressed those issues in a big way with a greatly improved resolution that gave birth to an extraordinary sense of air and sparkle when it was present in the recording.

The new, highly acclaimed Zen Widow IV-(from one dark age to another) LP was stunning with its presence in my listening room, and very much in the tradition of Nordic jazz that I've come to love at the Rochester International Jazz Festival. Hearts of Space on NPR was like a free trip on Virgin Galactic with increased transparency and a more voluminous soundscape. Thankfully, the Backert preamps will not deplete the oxygen in your listening room. Just remember to keep breathing as you listen.

The major accomplishment was the increased and seamless resolution from top to bottom when the Rhumba Extreme was added. Combined with the other qualities mentioned above, it brought the performance of the Acora speakers up to the level I have experienced at shows with much more expensive components driving them. Those rigs have typically cost several hundred thousand dollars – far more than my own. Of course, they were in much larger rooms in most cases and there is an economy of scale when you come home to roost after attending an audio show.

I'm grateful for being able to get such quality out of 18 Watts per channel from the parallel 300B tubes of Eddie Wong's amps, or 200 Watts from each (into the 4 Ohm speakers) with the AGD GaNFET monoblocks. The point here goes back to what I said earlier about trying to evaluate a Backert Labs preamp at a show. They deserve to be displayed with much more expensive components than their price tags suggest. And that's a trick if you don't have a power amp to match up with a primo speaker manufacturer and some top-flight front ends.


Power Cords
Using the same Synergistic Research Atmosphere Excite SX power cord (and interconnects) that I used with the Coincident preamp, the Rhumba Extreme exhibited very high resolution and transparency – two key characteristics I favor with my aging Boomer ears. It gives a ‘you are there' presentation that commands your attention like being at a live performance. It was not a laid-back and relaxed experience, nor was it irritating. The music was so clean my brain was not cognitively challenged to interpret lyrics unless the performer was deliberately singing with an affectation. Even old blues singers were a lot more intelligible.

The treble, meaning violins, cymbals, and brushes on drums, was also more prominent which might suggest to some that the signal was bright, but for me, it came across as revealing, not as being louder than the preceding octaves. I could hear more detail at a lower volume than ever before although I chose to continue listening at my usual 85dB to 92dB range because that gives me more of a live concert perspective, even though much of what I hear at JazzFest climbs upwards of 100dB in many venues, depending on where I sit.

I also had Audio Sensibility's new top power cord, the Signature SE Power Cable ($945) which is a copper conductor model, unlike the Synergistic power cord which uses silver conductors. With the Audio Sensibility power cord, the music was a bit warmer and the top end was noticeably rolled off, missing the sparkle and top-end air of the Synergistic cable. In other regards, it was an excellent cable with great resolution and fine transparency with an overall sonic signature that was very relaxing. The exercise clearly exposed the typical difference between silver and copper power cords, though each company also employs additional technologies that are quite different from each other.



In studying The Preamp Blog on the Backert Labs website they mention the break-in and testing of power cords they have done and why they have selected the power cord they include with their preamps. "What power cord is this?" I thought to myself. It turned out that it was wrapped in bubble wrap and never taken out of the shipping box. It looked like a typical imported stock power cord like those that inhabit the empty shipping boxes of other components in my basement. It is a 3-wire 18 gauge cord with molded ends, rated at 10A, 125V. Unlike most of these stock cords that come with new components, this one looked to have brass or gold-plated prongs and pressure plates. As mentioned in the blog, there was a tape around one end indicating the first day of the 30-day break-in they apply to each power cord. The next step was to give it a try.



I installed the generic power cable and fired up the rig, letting it settle in for 45 minutes before placing Stevie Ray Vaughan's "Tin Pan Alley" on the turntable. I wasn't expecting much, but man, was I surprised. It was a little on the warm side, but there was plenty of resolution, excellent sound staging, very good dynamics, excellent transparency, good attack, great decay, plenty of bloom and sense of space, and the tonal balance was very good without any hint that the treble was too bright. The pace, rhythm and timing were very inviting and overall it was very musical. I expect that a wide swath of audiophiles will find it quite sufficient. And I highly recommend giving this supplied power cord a long audition before considering spending money on another power cord, regardless of price. And certainly, only buy with a return privilege. Andy later confided that they burn-in the power cords on a Class A amplifier, rather than using a special modulating burn-in device.

As an afterthought, I turned the phono stage off and turned the volume knob up full. I had to place my ear an inch from the speaker to hear the slightest bit of noise with the tube power amps running. That Bob Backert was able to make this preamp sound so good with a generic power cord (though I did note that the blades seem to be gold plated, unlike most) is a testament to its superior design.


Tube Rolling
While I consider myself a tube guy, I'm not a tube expert. I take what tubes come stock with components and work with them that way. All the Backert preamps are designed for easy tube rolling with the previously mentioned portal accessible on top with an easily removed polycarbonate cover held in place with magnets. Andy Tebbe strongly encouraged me to try some tube rolling and sent along three pairs of NOS tubes. How could I not try them?



Neither the stock tubes nor the pairs sent for comparison were from Russia. With the Russian invasion of Ukraine, I will not review any components with tubes from Russia.

Each pair was in a presentation box with foam cut away to cradle each tube separately. A Sticky-Note was attached to each box indicating the tube and a few words to give me a hint as to what to expect, which I've put in italics. I also noted the labeling carefully in case you'd like to compare notes with tubes you already use or have on hand. Listening to these tubes was done using the Synergistic Research power cord, not the stock power cord that was discovered later but I expect the results would be very similar.


Listening To...
To begin, with the stock tubes still installed, I listened to Stevie Ray Vaughan's "Tin Pan Alley" because, well, it's a war horse with a large number of sonic cues to reveal the differences between the various tubes. Plus, I have a good LP copy. And hey, you've probably heard it and know it well yourself. My comments below on these NOS tubes were all in relation to the stock tube.

The first tube was labeled "RCA Black Plates, Refined, pretty." Printed on it was 5814A and handwritten on one were the test numbers "100/102". Compared to the stock tube I found this tube had more bloom, and was more liquid (especially in the decay). The bass was more bloated and more prominent. There was more echo in the guitar section right before SRV started singing. The attack was not as sharp. The ambient venue (background) was not as clean. It was like listening with a shot of scotch whiskey in me, though I never consume alcohol when I do critical listening.

The second tube was labeled "Hewlett Packard red print, A slight adrenaline boost. Refined." Also printed on the tubes was "5963, Made in Japan" and on one tube, "Toshiba 8A," and the other, "Toshiba 61." Compared to the stock tube, these were even more clean and clear. Strong attack with complete control of the notes. Great air and good bloom. Excellent resolution. Not overly liquid. Notes felt very authentic (great timbre), natural, and dynamic! Excellent soundstage. The song ended too soon!

The third tube was labeled "Green Print, Fun warm bass+" In green print on one tube was "JAN 5963, Sylvania, U.S.A. 341 7" and the numbers in vertical alignment: 7926. And in silver print above the green print: "5963 U.S.A."  The second tube in this pair had in green print: "U.S.A. 5963, Made in U.S.A. Sylvania" and the numbers 6342 vertically aligned. In silver, like the first tube: "5963 U.S.A."  This tube was natural, with good decay and good attack (but not as sharp). Smooth, good echo in the intro, a great "all-arounder," middle of the road, good resolution, good bass, but not overly prominent bass.

I then returned to the stock tubes and made the following notes:  "Fast attack, high resolution (including the decay), very present, excellent echo in the intro, very good soundstage. SRV was right in the room. Excellent inner detail. The top end is slightly prominent. Most like a studio feed. Tight bass.Neutral and very real sounding – not liquid. Again, the song ended too soon. Wow! Most impressive. A Best In Show contender."

My intent here is not to review these tubes, but to show that the Rhumba Extreme (and probably their other preamps) are very revealing of different tubes. Along with your selection of power cord, tubes offer yet another way to fine-tune the performance of the preamp. Andy asked me which tube was my favorite. I can easily live with the stock tube forever, but I can also acknowledge that others may differ. I prefer a "being there" experience while others may enjoy a more relaxing, soothing sonic signature...or something in between.

I haven't mentioned the stock tube by brand because, while they are reasonably plentiful, Andy doesn't want the price driven up by hoarders. The circuitry of the Backert amps is very easy on tubes and the warm-up time is minimal, so there is little likelihood you will need to keep a spare set on hand.



To Preamp, Or Not To Preamp?
There is a question of better sound with the preamplifier installed, rather than running the source directly to the power amplifier. This assumes your DAC or Phono Stage has a volume control, of course. Both of mine do, so I thought I would give this test a try. It wasn't quite an ‘apples to apples' comparison, but it does shed some light on the issue. Because of the positioning of the DAC and Phono Stage and the cables I had on hand, I wasn't able to use the same amp with both sources without moving a lot of components around to keep the cables and amplifier the same for each source. I chose not to tear apart my system but rather go with the same brand and model of cables, and use the different amplifiers. Here, again, I was using a Synergistic Research power cord with the preamp. Remember, the goal was to see if the source sounded better with or without the preamp in each case.

With the Coincident Statement Phono stage, I ran single-ended Synergistic Research Atmosphere Excite SX cables to the Backert preamp that was connected to my tube monoblocks with an identical single-ended interconnect. I listened to a series of cuts on a variety of LPs I play frequently. Then I ran the Coincident Phono stage directly to the same tube monoblocks using the same Synergistic interconnects. The same music was still good, but it lost a bit of transparency and presence as well as some dynamics – the things you normally expect to gain from a good preamp. This replicated the results I had when I ran this same test with the Coincident Statement Line Stage when I first purchased the Coincident phono stage.

Next, using my LampizatOr Amber 4 DAC with balanced versions of the same Synergistic interconnects running to the Backert preamp that was connected with identical balanced interconnects to the AGD Audion monoblocks, I listened to a series of cuts from my compilation CD. Then I removed the Backert preamp from the equation and ran the DAC directly to the AGD monoblocks with the same balanced interconnects. This time, to my surprise, the sound quality took a step up with a more holographic soundstage, a little more three-dimensionality to the instruments, a bit more inner detail, and a greater sense that I was listening to real musicians playing real instruments – more of that "Being there" that I love.

Well, how shall I spin these results? First, even the entry-level DAC in the LampizatOr line is a great DAC. Second, maybe I should just leave the tuner and phono stage running through the Rhumba Extreme to the tube amps, and run the digital side through the DAC straight to the AGD monoblocks. This would certainly complicate the speaker cable situation but each source would then be optimized. Or, I could simply run everything through the Rhumba Extreme and accept the slight degradation of the CDs. If I didn't tell my friends, they would never know. Oh, my. More of these first-world decisions. But the story isn't quite over.


Classical Music?
As I began to wrap up this review it occurred to me that I hadn't seriously listened to any classical music with the Rhumba Extreme. Surely there are a significant number of people who still listen to classical music. I returned to the listening room with the Rhumba Extreme still connected with the stock power cord and selected Brahms' Fourth Symphony, E minor, Opus 98 with Szell conducting the Cleveland Orchestra from the CBS Great Performances series.  It was both re-mixed from the three-track tape master using Dolby System and re-mastered. It's a mint copy.

I haven't been a big fan of classical music to this point, but having heard the Cleveland Orchestra live once, I'd say this LP recreated the splendor and magnitude of this renowned orchestra. The transparency, resolution, and soundscape offered by the Rhumba Extreme was a welcomed invitation to explore the hundreds of classical music LPs I collected at garage sales back in the 1990s. It is a lot more interesting on a high-resolution system with great dynamics such as I was now hearing.


Breakthrough With Digital Playback
The opening of the Fourth Movement of Mahler's First Symphony on my compilation CD is a piece I'm much more familiar with and running the rig with the Rhumba Extreme produced the most impressive and emotionally inviting audition I've ever had with this segment, becoming more three-dimensional, layered, dynamic and with more tonal color and sense of presence than ever before... and "ever before" is at least a hundred times, maybe two hundred.

Realizing I was listening to my compilation CD for the first time with the stock power cord, I ran through most of it one more time, omitting only the dynamic rap cut and Hugh Masekela's "Stimela" in the interest of time. The digital playback had risen to an all-time high with this basic power cord. Unbelievable! Except that's what I heard. Eager to compare digital playback with a modern pressing of an LP, I grabbed Niel Young's Live At Massey Hall, 1971. Lowering the needle on "Old Man" two days before Father's Day was a mistake – a big, beautiful, emotional mistake. I let the record play on until my wife, who had been working outside, came in and handed me a note saying "Please go get a fish fry. I can't cook dinner and paint the deck, too."

With the seemingly ordinary off-the-shelf power cord, the Rhumba Extreme has brought my system to a new peak of performance, in terms of sound quality, emotional involvement, and enjoyment of the music. And that issue with the DAC sounding better going straight into the amps? The stock power cord didn't solve that problem – it destroyed it!



The Question Of Value
The Backert Labs Rhumba Extreme 1.4 preamplifier costs a significant amount of money for most people in this hobby. You could assemble a very nice-sounding rig for what this preamp alone costs. You could spend multiples of its cost for a pricier preamp from another brand. And you can go up or down a price point within the Backert Labs brand. Am I starting to sound like a "middle-of-the-road" kind of guy? Don't be fooled. Hear it for yourself if you can.

The Backert preamps offer a lot of connectivity options which may be very important if your system is growing. It also offers tuning options with different tubes, cables, and footers. Who knows – maybe your taste in sound quality or source preference will change in a few years? That's when the value of the flexibility of this preamp will pay dividends. You won't be trading it in any time soon.

As a reviewer, the connectivity options of the Backert line of preamps make a compelling story. But more importantly, I found the Rhumba Extreme stereo preamplifier will elevate more moderately priced gear to play in a league with far more expensive equipment if you've curated your system wisely. It delivers the transparency, spatiality, liquidity, and palpability that great tube gear is known for. If your speakers require a powerful solid-state amp, this tube preamp will give you a great shot at having the best of both worlds.

And if you're lucky enough to have speakers that can be driven with an affordable tube amp, Backert Labs' Rhumba Extreme 1.4 preamplifier may very well be your end game. In my rig it has brought me closer than ever before to experiencing the presence of live performances in my own home, revealing inner detail and evoking more emotional response to the music than ever before. That it does so with its stock power cord leaves me flabbergasted.

While there are just two handfuls of dealers, primarily in the East, which makes it difficult to audition, Bob offers a 14-day home trial period with your purchase. In the past, Backert Labs has appeared only at Capital Audiofest, but in my opinion, which rests on 30 years of reviewing audio shows, the Rhumba Extreme 1.4 preamplifier can hold its own among the very best of rigs and should be heard at shows across the country. If you're worried about selling yourself short, let me invite you to step up to their flagship model, the Rhythm.

Sunday morning I fired up my vintage Suzuki motorcycle and rode over to inspect a decades newer, nearly flawless red Ducati with only 2700 miles on it. It was lighter and more maneuverable, but the hand grips were narrow, and the seat was hard – great for canyon carving but not the sort of bike for riding hundreds of miles up to the Adirondacks. As I rode home I realized how much I love my old Suzuki with its wider seat – almost as comfortable as my listening chair. And besides, I'll be spending a lot more time listening to music than riding motorcycles over the next decade. I cut the check instead, to Backert Labs and purchased the Backert Labs Rhumba Extreme 1.4 vacuum tube preamplifier.





Sub–bass (10Hz – 60Hz)

Mid–bass (80Hz – 200Hz)

Midrange (200Hz – 3,000Hz)

High Frequencies (3,000Hz On Up)



Inner Resolution

Soundscape Width Front

Soundscape Width Rear
Soundscape Depth

Soundscape Extension Into Room


Fit And Finish

Emotionally Engaging 
Self Noise

Value For The Money



Type: Vacuum tube stereo preamplifier
THD +N: 0.09%
Frequency Response: 7 Hz to 112 kHz (+/-1dB)
Channel Separation: -82dB 
S/N Ratio: 98dB referenced to 2.5V output, 90dB/1V
Gain: 9dB
Input Impedance: 43 kOhms
Output Impedance: Below 80 Ohms
Chassis Dimensions: 17" x 14" x 4" (WxDxH) add 4.875" with feet
Weight: 24.4 lbs.
Price: $8500 (blue or red chassis adds $300)




Company Information
Backert Labs
501 Gibben Road
Hockessin, DE 19707

Voice: (302) 723-7549
E-mail: info@BackertLabs.com 
Website: BackertLabs.com















































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