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April 2016
Enjoy the Music.com Review Magazine
iFi Audio Retro System: Stereo 50 Integrated Amp/DAC And LS3.5 Speakers
Retro coolness at vintage pricing.

Review By Dwayne Carter


iFi Audio Retro System: Stereo 50 Integrated Amp/DAC And LS3.5 Speakers Review

  I think Enjoy the Music.com's Creative Director is trying to kill me, or at least drive me insane (Steven says "There's a stairway to heaven and a highway to hell. I race cars and hate the StairMaster). At the very least, he has an odd sense of humor (who, moi?). For those of you in the know, and remember my featured article, The Awakening; the story of Rip Van Winkle describes my present mental state as I've been away from the high-end audio industry for quite a few years. So what is the first piece of gear my editor sends me to review? The iFi Retro System that consists of their Stereo 50 and LS3.5 speakers. The key word being retro. It looks like something from the 1970's. Seriously.


Let's Start At The Beginning Shall We?
iFi Audio's Retro System consists of the Stereo 50, which is a controller, preamplifier and amplifier all within a single box. It also includes a pair of their LS3.5 loudspeakers. Calling the Stereo 50 a preamp is an understatement, so I choose to add in calling it a controller. The Stereo 50 is an all-in-one vacuum tube amp controller. Yep, vacuum tubes. Not that new-fangled solid-state stuff, but vacuum tubes (or valves for those on the other side of the pond). The iFi Audio Stereo 50 controller has a pair ECF82 and four EL84X vacuum tubes that, in total, produce two channels @ 25 Wpc. Also here for review is a pair of LS3.5 speakers. This design harks back decades and this specific bookshelf-sized speaker pair felt heavy and solid right out of the box. Once I got them out of the box. If you are fortunate enough to have the pleasure of unboxing the iFi Audio Stereo Retro 50 and/or the LS3.5 speakers; allow yourself some time. You'll need it. The iFi Audio Retro System arrived double boxed and well wrapped. After removing the layers of foam and protective cardboard, you'll be delighted to find all the components carefully wrapped in a thick, cloth bag. Very nice! The attention to detail was obvious from this moment on. The finish on both products? Impeccable and very nice. Inside the Stereo 50 box you'll find plenty of accessories plus at the top is a "Quick Start" guide! YES!!


iFi Audio Retro System: Stereo 50 Integrated Amp/DAC


You'll also find a small remote control, cables (USB, RCA interlink, and mini jack), a TosLink adaptor and speaker cables. Yes, speaker cables. They looked so impressive that I replaced my existing office speaker cables (no name brand worth mentioning) with the iFi Audio Retro Stereo 50 supplied cables. Not sure what brand they were, but I later learned that they were Teflon isolated, silver plated copper cables; so it was a no-brainer to replace my generic cables. Considering the LS3.5 speaker size, and the total power output of 25 watts per channel from the Stereo 50 controller, my office would be the ideal location for auditioning. I later learned that the iFi Audio Retro system could easily fill a room twice the size of my office, but for now, the office it is.


iFi Audio Retro System: Stereo 50 Integrated Amp/DAC Review


The Stereo 50 easily fits on my desk, with the unit being about the size of a country mailbox. Surrounded by my three monitors and Crestron controller, the Stereo 50 looks a bit out of place. While we are accustomed to our speakers made of wood, the LS3.5 are actually made of bamboo... but more on that, later. On modern-day gear, we're not accustomed to seeing our preamp / amplifiers covered in wood as well!


Design Details
From the front, you are treated to a minimalist dream. Four large knobs, five seemingly circa 1970 'stick' selector switches, two headphone jacks (both 3.5mm and 6.3mm) and a 3.5mm Analog Input jack (shared with Input 2 on the rear). That's it. From the back of the unit... oh my! This is the reason I call the Stereo 50 a controller. You are treated to a smartly laid out connection panel. Speaker terminals are in the middle yet smartly up and out of the way. To your left, you have a combination of analog and digital inputs. You'll also need to attach the supplied Bluetooth antenna. Next to the Bluetooth pairing button, you'll find a nice pairing of Phono inputs (MC Low, MC High/Line Input 3), Input 2, S/PDIF Coaxial, TosLink optical, and USB. You'll also see logo's for virtually every digital format available today. My immediate reaction was to plug something in and play some music!

Power her on and in approximately 50 seconds the vacuum tubes come to a full glow. Oh year, my first tube experience in many years! Disconnecting my Meridian Explorer DAC from my Mac, and plugging in the Audioquest Forest USB cable into the back of the Stereo 50 and I was ready for some music! Opening up my Hi-Res software (Audirvana Plus), I cue Natalie Merchants "Tigerlily" in FLAC 24-bit/96kHz. The sound was...... silent. I heard nothing. Nada. Checking the connections was the first order of business. All in order, all connected correctly. Looking at the faceplate, everything appeared to be in order. But wait. No it's not. The Digital Input selector switch was set for Coaxial/Optical instead of USB? How could I make such a critical mistake? Was I blind? Well as a matter of fact....

At this point, here is my first (and few) "Con" with the Stereo 50 (other than the whole retro 1970's look that is freakin' me out! Thanks Steven!). In certain lighting conditions the faceplate of the iFi Audio Retro Stereo 50 is difficult to read. At times, darn near impossible. Now, it could be my aging eyes, or it could be the pendant lighting in my office. The fact of the matter is, you might need a flashlight to view the faceplate from time to time depending on your lighting until you get familiar with the knobs and buttons. No big deal. I selected USB and there be music!

Selecting the wrong input switch was a minor issue that plagued me throughout the review. The Stereo 50 actually has three inputs (Direct Input, Digital Input and the large round knob labeled INPUT). Because the Stereo 50 can play virtually every source and format available today, it stands to reason that you will need a variety of input switches. To access the Digital Inputs (Bluetooth, Coaxial/Optical and USB), you need to move the large round knob to Input selection one, then click the small retro switch to either Bluetooth, Coaxial/Optical or USB. Switching the large knob to Input 2, 3 or Phono and you get nothing. In my case, I had the knob turned to Input 1, but my retro switch to Coaxial/Optical. No big deal. It's a simple "selector check" when changing sources. No worries.

The review sample was brand new, so I set the playlist to random and let is play (at low volume) for the week. Yep, the entire week. Work was busting my chops, so it was easy to do. Come Saturday morning, the wife was off to work, and I was ready to do some serious listening! Double checking the Tone Controls (Bass and Treble) were in the neutral position (and remained that way throughout most of the review), I was ready to start my listening session. Preferring to listen to my "Review Playlist" as neutral as possible, I opted to switch the Direct Input switch to the off position. It remained this way for most of my review process.

There was a few steps needed before music could be summoned. You see, the Stereo 50 also has an XBass switch, as well as a 3D switch. Not knowing what they were for, yet (and getting a bit antsy) I turned both selectors to off and started with my official "Review Playlist". After reading the manual, I later learned what they were for. More on these features, later. To introduce a bit of commonality and objectivity into my review process, I have started a playlist of Hi-Res Music and CD quality music. It's a collection of songs I know well, and have listened to many, many times. I start with the Hi-Res collection and worked my way down (in quality). It's easier for me to hear what's missing, than what was "added". It's my process and it works for me.


Retro Music
Cappuccino in hand and after several hours of blissful listening, I began to forget about the review process and just enjoy the music (grin).... and I did. I wafted through my first Hi-Res Music piece, Michael Jackson's Thriller (DSD64). Then on to Tom Petty's Full Moon Fever (FLAC 24-bit/96kHz), to Billy Joel's The Stranger (AIFF 24-bit/88.2kHz) and after two hours of Hi-Res heaven; Leclair's Sonata for 2 Violins in G Major (AIFF 24-bit/96kHz). When listen to Hi-Res Music via USB or Digital Audio a dim LED will glow on the front panel. The coloring will be green, yellow, cyan, magenta or white depending on your format/file type. Nice touch, iFi Audio!

Finishing my Hi-Res Music list with classical music, I continued my first listening session with CD quality music (WAVE 16-bit/44.1kHz) and worked my way to bass dropping Rap. The Planets by Holst: War to Young Jeezy's Put On. The Retro Stereo 50 controller and the LS3.5 Speakers took everything I could throw at it. Except for the booming Rap. Let's talk about that, and the bookshelf-sized iFi Audio LS3.5 Speakers.


iFi Audio Retro System LS3.5 Speakers Review


The Stereo 50 comes with a pair of small speakers called the Retro LS3.5. Apparently, they are a reboot of a former product (the LS3/5a). The speakers are small, but well-built and solid. On the iFi Audio website they mention the speaker's cabinet being comprised of bamboo, thus making them eco-friendly as well as knuckle crushingly solid. I replaced my old office speakers Jamo Concert 8 and used the iFi Audio supplied speaker cables. The LS3.5's are almost half the size of my old Jamo's! The speaker use two iFi Audio drivers that consist of a  4.5" paper cone midrange/woofer driver and a 1.1" waveguide-loaded silk dome tweeter. Around back, you'll find the sturdy speaker terminal and a rectangular Bass port. The LS3.5 speakers maintained a very straight forward, very clear, and very even sound. Very flat, like studio monitors. As an old studio rat, I prefer that sound. I don't like any extra "color" to my music, unless I added it (via a Tone Control or the like). But don't worry. If you like some extra sauce, the Retro 50 can provide that as well.

Hour after hour, day after day, the combo of the Stereo 50 and LS3.5 speakers provided me with clear and balanced sound. As one gets older, high frequencies become more of an annoyance. With that sensitivity in mind, the LS3.5 speakers started out a bit shrill and peaky. Over the next few weeks they evened out nicely. Midrange and mid-bass are clearly where the LS3.5's live. There is a smooth transition from the mid's to the beginning of the bass range that was a constant note on my cheat-sheet.

Sub-bass? Ah yes, sub-bass. Let me point out, that these are bookshelf sized speakers, folks. You can "Drop That Bass" all you want, but the LS3.5's are really not down with that or designed for that. They output a considerable amount of mid-bass for their size, but it not a chest thumper session. Considering the LS3.5's are placed on my desk, I'd rather not experience heart palpitations while I work, thank you very much!


iFi Audio Retro System: Stereo 50 Integrated Amp/DAC


So what is my overall sound impression of the Stereo 50 and LS3.5 system? Balanced, controlled, and neutral. Oh, did I mention the speakers come with both a black and silver grills? Your choice. Just change colors at will. I spent the remainder of my reviewing time, just getting to know and understand the Stereo 50's impressive capabilities. This little shoebox can do it all!

What do you want to plug in? Your PC or Mac? No problem! Stream music from your phone via Bluetooth? Done! CD player, DVD player, or Blu-ray player? Check, Check and Check. What about pure analog? You know who you are. Dusting off your old turntable and record collection? The iFi Audio Stereo 50 has an extensive collection of refinements for virtually any turntable you choose to connect. My old Technics SL-D3 turntable was not a challenge for the Stereo 50. As a matter of fact, with the obviously well thought out Phono Input choices available on the Stereo 50, I felt a bit embarrassed hooking up my old Technics (I do have my eye on the limited addition Queen Rega RP1, though).  But, considering I no longer have an album cleaner, and an even more questionable cartridge, I kept my phono session as brief as possible.

To explain all of your phono options would take the rest of the space I'm allowed in this review. Suffice it say, the excellent manual (available for download from their website) will walk you through all your possible choices; step by step. MC Low, MC High, MM; whatever you have. Cartridge rated output of <0.75mV? Then you select the Mode Switch to MC Low (on the back). >3mV? Then you choose the MM selection. Me? I didn't have a clue. I'm not going to lie. I guessed MC Low and got sound.

Phono God I am not... yet. One thing at a time please. The phonostage on the iFi Audio Stereo 50 was not an after-thought as found within so many other products. This was designed from the white paper phase on up. To be honest, I was so impressed with the sheer amount of technology they crammed into this little box, I hope my editor allows me to list the entire list of features:

High-quality wireless Bluetooth (aptX) with NFC for pairing..

Pure vacuum tube 25W + 25W amplifier.

Pure vacuum tube headphone Turbo 7,000 mW output power; able to drive even the most difficult of headphones.

Native Octa-DSD512 (24MHz), PCM768kHz, 2xDXD, the most advanced digital audio formats available are supported together with all other DSD, PCM and DXD formats available.

Minimum phase, minimum ringing digital filter is employed for PCM up to 192kHz. Pure analog, no-ringing filtering is used for DXD/2xDXD as well as DSD.

High-resolution audio USB, Coaxial, Optical digital inputs.

3D Holographic Sound Systems for Headphones and Speakers.

XBass for the best bass and dynamically corrects the Bass response to match the human hearing.

Ultra-wide gain range MM/MC phono pre-amplifier, able to match all phono cartridges.

Precision studio-grade tone controls.

Analog volume control with remote control.


Magical Music Via CIEMs And Headphones
Headphone lovers? Yep, they've got you covered. Because I was reviewing the Stereo 50 and the LS3.5's as a system, I kept my headphone listening to a just a few hours. I had recently received my Noble Audio Kaiser 10 CIEMs (Steve sez "Out of the seven or so CIEMs here the Noble K-10 are still my faves with top-line Double Helix silver cabling. You are getting Double Helix cables Dwayne, yes?).



So far, I had only listened to the Noble Kaiser 10 CIEMs at the gym with the iPod Classic via MP3 files (HEY...DON'T JUDGE ME!); I was eager to listen to some Hi-Res Music! The Stereo 50 has inputs for both 3.5mm and 6.3mm, so you're covered either way. How did my Noble K-10 CIEMs sound? First of all, the Noble Audio Kaiser 10 CIEMs are some of very finest CIEM's you can buy. Match them with the iFi Audio Stereo 50 and you have a killer combo! Hands down. By the by I've order a Questyle QP-1R portable DAC so the iPod is on the ropes. Are you happy now?! (Steve sez "Yes, took you long enough." ;-)  )

Time to circle back around to the Tone Controls, XBass and 3D Switch. Earlier (as is my normal process), I switched on the 'Direct Input' selection, which removes any tone control from the signal path. Switching it back on, it was now time to play. Tone controls were very accurate sounding, with nice, click-indent knobs. You can control the Bass and Treble, with +/- 8dB of emphasis (or de-emphasis at 100Hz or 10kHz, respectively). Turning both back to 0db, it was now time to turn on the XBass and 3D systems.

Both, the XBass and 3D systems, were originally designed to enhance the headphone user experience. Putting in my Noble Audio Kaiser 10 CIEM's, I selected the 3D enhancement, first. Selecting the lower of the two 3D settings, I listed to a few tracks from my Review List. A slight "expansion of space" was detected. It was as if, the inside of my head grew a bit larger. Swapping out my CIEM's for my old, over the ear Koss headphones; I tried it again. Oh, there it is! The great thing about CIEMs is that the sound is projected so deep within your ear canal that it feels like the soundscape had formed within the middle of my brain. Pulling the sound projection to the outside of your head allowed the 3D enhancement to do its job. Instantly, the sound field moved towards the center of my head. After only a few songs, I was forced to remove my old Koss headphones since the incredible Noble Audio Kaiser 10 CIEMs have spoiled me.


Subwoofer Sounds
When auditioning the XBass system, I moved the entire system to my Great Room. Here in the southwest, many homes have a Great Room. It's a large living room, yet why do they call it a Great Room? Well, probably because the ceilings are 21 feet high at their peak. This room may not be totally acoustically neutral or ideal, yet the Great Room does have my nice Salamander AV center, Martin Logan speakers, Bryston amplifier, and for the sake of this review my Velodyne subwoofer. Quickly setting up the system, I soon discovered the only missing output on the Stereo 50 is a subwoofer output.  No worries, I would simply use the speaker-level output to the subwoofer, and then to the LS3.5 loudspeakers. For right now, and using the speaker wires from the Stereo 50 to the LS3.5 Speakers. Turning on the XBass circuit and then selecting the lower setting first, followed by the higher setting. My understanding is that the higher setting is for when you standmount the LS3.5 speakers. The XBass selection provided a nice low-end boost to all types of music I auditioned. It wasn't your typical low-fi "loudness" EQ feel. The XBass enhancement felt as if it was custom tailored for the LS3.5 speakers (which it was). I found myself leaving the XBass selection on for the remainder of this listening session. Connecting my big 18" Velodyne subwoofer as described I could never get it to balance perfectly well with the LS3.5 speakers. A smaller subwoofer would have worked much better. The 3D enhancement didn't have a positive effect in my Great Room, either, yet that room is nearly acoustically impossible if you're trying to achieve perfection. Under normal circumstances (and a ceiling that isn't pitched to a 21 foot peak), the 3D enhancement would have done its job extremely well.


So how do I wrap up my experience with the iFi Audio Stereo 50 and LS3.5 speakers? Well, I was sad to return them and miss having the ability to listen to virtually any source, in any format, at any time. What about the company iFi Audio? My contact with them has been truly top notch. Very detail oriented like their products. Yes, as a reviewer I might get a little special attention and was notified of a firmware update and guided through the simple update process, but this company and their distributors obviously have their act together. Their owner's manual is excellent! I'm serious. Download it if you don't believe me.


iFi Audio Retro System: Stereo 50 Integrated Amp/DAC And LS3.5 Speakers


This is how you write an owner's manual. I can't tell you how many times I'm ready to spit bullets trying to figure out what this or that knob does with other gear! Really! Being vague is not cool. It doesn't make me think your product is exclusive. It makes me angry that you have to spend 20 minutes trying to figure out what this thing is for! Write it down and point me to the damn manual! iFi Audio even has a repair ticketing system on their website. Have a problem? Simply open a ticket and track your repair just like at the office, but without the IT Geek and his rolling eyes and disgusted sneer. I can say that because I was one of them, so we're all good.

So I bet you're wondering how much all this coolness costs? The iFi Audio Stereo 50 and LS3.5 speakers (sold as a set), will set you back a whole $1995. Yep, under $2k and that's a great bargain! The big question is, would I make it mine? Would I own the iFi Audio Stereo 50 and LS3.5 speakers? Good question! The best answer is, I'm Ducati guy staring at a dressed-out Harley. While I appreciate and respect the Harley, am always going to like the look of the Ducati (the 900ss ie, naturally). The Retro look is just not my thing, but the guts of the Stereo 50 are. Now, cram all this into a gloss, piano black aluminum shell (leaving an opening on top for the glowing tubes) and I'm in!



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 Behind Speakers

Soundscape Extension Into Room


Fit And Finish

Self Noise

Value For The Money


Type: Vacuum tube stereo integrated amplifier with DAC and two-way loudspeakers
Wireless Input
Bluetooth (aptX)

Digital Inputs: USB (DSD512/768kHz/2xDXD), S/PDIF coaxial and TosLink optical (192kHz)

Analog Inputs: Phono (MM/MC), two line inputs and a 3.5mm (shares with Line 2)

Outputs: Loudspeaker and 3.5mm / 6.3mm headphone

Audio Section 
Power output (Music) > 25W (majority Class A)
Total Harmonic Distortion: < 0.2% (@ 2.83V/1W)
Output Bandwidth: 10Hz to 60kHz
Frequency Response: 10Hz to 80kHz
Signal-to-Noise Ratio: > Amplifier 101dB (@ max output)
    > Phono MM: 90dB(A)
    > Phono MC: 80dB(A)
DAC Dynamic Range: > 113dB(A)
Tone Control Bass: +/-8dB @ 100Hz
Treble: +/-8dB @ 10kHz
Analogue Signal Processing (ASP) XBass, 3D Holographic
Phono Gain 38, 50, and 62 dB
MM: 220pF//47k
MC: 200pF//330R
RIAA Accuracy: <0.5dB
Vacuum Tubes: Two ECF82 and four EL84X

Digital Section 
PCM: 44.1kHz to 768kHz
DSD: 2.8MHz to 512MHz
DXD: 352.8kHz to 768kHz
Filters Minimum Phase (PCM 192/176.4/96/88.2/48/44.1kHz)
Bit Perfect (DXD / PCM 768/705.6/384/352.8)
Analog (DSD)

Power Supply AC 100V-240V
Dimensions: 300 x 153 x 226mm (WxHxD)
Weight: 12.75 lbs. 
Price: $1995


Company Information
ifi Audio
E-mail: contact@ifi-audio.com
Website: www.iFi-Audio.com













































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