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January 2021

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Nagra Tube DAC And Classic PSU Power Supply
Sonic glory... worth it!
Review By Tom Lyle


Nagra Tube DAC And Classic PSU Power Supply Review


  Nagra is a Swiss audio equipment manufacturer that has been in business for over 65 years. Their professional portable tape recorders were an industry standard for many decades, even appearing as props in many films and television shows. Their reputation was rock-solid even before they started manufacturing high-end audio equipment in the 21st Century.

Because of this, and because of the fine high-end audio components they've been designing and manufacturing since 2012, I suppose there are many audiophiles, and plenty of non-audiophile, who might add the Nagra Tube DAC and its matching Classic PSU power supply to their systems without an audition, or without reading reviews on the subject. They might not even discuss this purchase with anyone else, other than perhaps their significant other.


Less than two years ago I reviewed Nagra's most current linestage, the Enjoy The Music Legendary Performance award-winning Nagra Classic Preamp. Ever since then, it has become my reference. I didn't need much convincing to accept the assignment to review the Nagra Tube DAC / Classic PSU package. Nagra calls this DAC a "no compromise design", and after living with it for a few months I'm forced to agree with them, even if just considering its sonic aptitude, which I'll discuss in more detail in a bit.

The Nagra Tube DAC is essentially a two-cabinet component. It is powered by their Classic PSU, which supplies optimal power to the converter. The Classic PSU can not only supply power to the Tube DAC but also can be used with Nagra's VPS phono stage, their JAZZ and Melody preamplifiers, their Classic DAC and HD DAC converters. Because the Classic PSU has three outputs, I was also able to enjoy the instantly recognizable increase in sound quality when I used it to power the Classic Preamp that currently lays down the law in my main system.


Nagra Tube DAC And Classic PSU Power Supply Review


Since this preamp has an IEC input on its rear panel, one can also use its internal power supply by connecting a power cord of one's choosing, and then plug that into an AC wall receptacle, or an outlet from any source of 110V AC, such as a power conditioner. The Nagra Tube DAC does not have an internal power supply, and instead, it relies on the Classic PSU to supply its juice.

In keeping with Nagra's no-compromise design or perhaps for reasons not completely understood by mere mortals like myself, the Tube DAC requires two power lines from the Classic PSU, one to power the digital circuit of the Tube DAC, the other to power its analog circuits, including its 12U7 vacuum tube (called an ECC82 tube in Europe). No compromise, indeed.


Inspired by the design of Nagra's HD DAC, the Tube DAC uses a new digital core built "on the experience gained" from that component. And so, the Tube DAC features an entirely new converter and a new USB interface. The result, says Nagra, is a "major improvement" in the sound of every digital format it converts, including Red Book CD via its S/PDIF coax input. I'm not sure it's worth mentioning that The Nagra Tube DAC can reproduce DSD 256 and 384kHz PCM signals, since all modern digital-to-analog converters worth considering these days can do so.


Nagra Tube DAC And Classic PSU Power Supply Review


Nagra insists that it's no-compromise design is not only in regards to its digital circuit, but its analog section as well. The normal use of steep slope filters has been done away with, and because of this, Nagra says that one can hear the transients and harmonics that were on the original recording, which translates into the music having a more life-like quality. On their website, Nagra continues touting its Tube DAC, by saying that it uses some very impressive internal parts, including "ultra-high" performance drivers, and hand-wound transformers. 


The Nagra Tube DAC / Classic PSU package was auditioned in my main system that is set up in my acoustically treated dedicated listening room. I might be overstating it a bit when I call it a "dedicated" listening room because there are other things in the room beside my system and my cheap but comfortable IKEA listening seat, but everything in the room is in the service of the audio system, which includes a desk and computer.

Also in the room is my large vinyl collection, which many consider acoustic room treatment, and the computer on the desk is a music server which is loaded with Foobar 2000 and J River Media software that sends a signal that comes through a USB port, which uses a Wireworld Platinum Starlight USB cable to send its signals to the Nagra Tube DAC's USB input. Also connected to the Nagra's rear panel, using an Accusound "Digital Link" 75-Ohm coax cable was an OPPO UDP-203 Blu-Ray/universal disc player, this way I could listen to the occasional SACD or audio DVD.

The Nagra Tube DAC was supported by the Nagra VFS (Vibration Free System) which consists of two base plates, placed one atop the other, meant to eliminate mechanical vibration in the component that is placed on it.  Nagra says that it was originally designed for sensitive components such as preamplifiers. There is also one under the Nagra Classic Preamp that was used in my system for this review. The fact that both the Classic Preamp and the Tube DAC both have vacuum tubes in their innards makes even more sense that one uses some sort of vibration control. I felt good using the Nagra VFS under the Nagra Tube DAC because it was manufactured by the same company as what it was protecting, plus the Nagra VFS made the industrial-chic looking Tube DAC look even more stylish! Between the hung shelves on my Arcici Suspense equipment rack and the Nagra VFS, I felt secure in the fact that vibrations were kept under control.


Nagra Tube DAC And Classic PSU Power Supply Review


The Nagra Tube DAC's analog outputs were connected to an input on the Nagra Classic Preamp or a Gryphon Essence preamplifier, and its signal was fed to either a 250 Watt per channel Pass Laboratories X250.8 or a Gryphon Essence power amplifier that put out "only" 50 Watts per channel, although it uses a Class A circuit (both the Gryphon preamp and power amp have reviews forthcoming). The power amp de jour fed a pair of Sound Lab Majestic 545 full-range electrostatic loudspeakers. Although the "full range" within their moniker is technically truthful, my varied taste (or lack thereof) in music means that the speaker's low-frequency extension to no lower than 32 Hz demands that I augment the speakers with a pair of subwoofers. And so, the more than sufficient SVSound SB16-Ultra did the trick, with their 16" drivers and 1500-Watt internal amps filling in the lowest frequencies down to 16 Hz (+/-3dB).

Other than what was mentioned above, at the beginning of the audition period, I started with Kimber Kable Carbon 8 interconnects, Carbon XL speaker cable, and Ascent power cables. About halfway through the audition period, I was sent for review Black Cat Graceline L2 interconnect and speaker cable. This didn't change the sound all that much, which spoke well for the Black Cat cable, but I was able to notice these differences and take that into account when judging the sound of the Nagra component.

I also used battery power supplies for some of the equipment, as the power set to our home from the electric company suffers from various sonic pollutants, especially during the day. During daylight hours I connected the power amplifier to the Goal Zero Yeti 1000 lithium battery power supply, at night the amps were plugged directly into the wall receptacle, which was one of two dedicated lines that run directly to our home's circuit box in the basement.

Some of the front-end equipment was often connected to a Rockpals 250-Watt portable lithium battery power supply (I now use this very reasonably priced unit instead of my older Goal Zero Yeti 400. Unlike the Goal Zero, it has no fan, so it is much quieter). Incidentally, when the Nagra equipment was connected to the Classic PSU power supply, I heard no sonic benefits at all from using the battery power supply, during the day or night time.


As many may know from my previous reviews, my digital music diet consists largely of files stored on several hard-drives hardwired via USB to the music server's computer. On these hard-drives are many terabytes of music, the large majority of these files are of "CD quality", in other words, 16-bit/44.1kHz. I also have lots of higher resolution files, and loads of DSD files - there are somewhere between three and four terabytes of DSD files residing on these drives. But I've been collecting CDs since the 1980s that have now been ripped, along with others downloaded from the internet via broadband. In just the "Rock" folder there are 17 terabytes of music stored on the drives.

This means that any DAC I use better sound pretty darn good when converting these lower resolution files. I don't mean that CDs should sound as good as DSD files, but that the converter should earn my praise just as much when playing either. Spoiler alert: The Swiss-made Nagra Tube DAC/Classic PSU combination renders the best digital sound I've ever heard in my system, from any DAC I've ever used, regardless of the file's resolution.


Nagra Tube DAC And Classic PSU Power Supply Review


No, I've never auditioned a ~$108,000 complete DSC Vivaldi digital playback system or its equivalent in my listening room. So, as I praise the Nagra as the best I've heard so far, I should mention that for the last two years I've been using a $25,000 EMM DA2 digital-to-analog converter. Even though it doesn't cost as much as a BMW M5, or a full DSC Vivaldi digital playback system, it reaches very far into the "excellent" category, where it is rather difficult to find fault with its sound. I've had many other DACs throughout the years, their sound quality incrementally improving. And even though I bet with many systems the difference between the EMM Labs and the Nagra might be measured in nuance. But still, the most significant improvement has been with the Nagra.

The Nagra Tube DAC / Classic PSU combo goes farther in making improvements in digital sound quality in my system, making instruments and voices sound very realistic, having a dynamic distance between sounds, and also entering the same category as the award-winning McIntosh MC611 solid-state monoblock amplifiers that both Enjoy the Music.com's creative director Steven R. Rochlin and I reviewed in the summer of 2018. In my review, I called these McIntosh amps "beautiful" sounding. As with the McIntosh, the Nagra Tube DAC system sounds more pleasing to the ear than any other DAC I've ever heard, anywhere near its price.

This "beauty" is not a coloration. When playing any files of well-recorded music, the Tube DAC does this with what sounds as close to absolute transparency as we're likely to get anywhere within its price range. No, this price range isn't low. But it translates into the overall sound quality having the gestalt of "real" sounding voices and music.

When I say that this DAC system sounds beautiful, I mean that it has the beauty of real music. When listening to a live instrument or voice it sounds pleasing to the ear. At least it should. Well-recorded music should also sound pleasing to the ear. Like real music (as long as it's not played too loud!). And this type of "reality" is what I assume is the goal of high-end audio! The Nagra Tube DAC/Classic PSU package comes closest to sounding like this than any other DAC I've ever had in my system, or heard in many other systems and within audio salons unless one considers digital systems costing much, much more.


I had a blast playing the DSD of Boulez Conducts Ravel a compilation on Sony Classical of recordings made in the 1970s with the New York Philharmonic and the Cleveland Orchestra. Believe it or not, there might be readers who are not familiar or only slightly familiar with these popular Ravel pieces that some classical music lovers might derogatorily call "warhorses", in other words, played so many times that they become overly familiar. We can remind those who say this that they have been played so often because they are very, very good works of music.



If one is unfamiliar, or only slightly familiar with Maurice Ravel's catalog this SACD is highly recommended. Another reason to recommend this SACD is that its sound quality is second to none. And the Nagra Tube DAC took full advantage of this. An amazing display of both microdynamics and macro-dynamics, yes, but also dynamic distance, where instruments that were located very close to each other in the Tube DAC's huge soundstage, but also seemed to be playing at the same volume, were separated by an appropriate distance within the front soundstage. This was very apparent in, for example, the climax of the familiar "Bolero", which is the first piece. I must have heard this piece played in concert and on my system a thousand times, and played through the Nagra Tube DAC I could hear details I wasn't familiar with coming from the rear of the orchestra; these instruments' location in the soundstage was located way beyond my rear wall.

On "La Valse", I could hear these traits even better than on "Bolero", as this piece is more of what I like about Ravel's impressionistic orchestration, the nebulous groupings of winds and strings, mixed with the occasional harp glissando, sonically painting with pastels outside the lines. The Nagra Tube DAC was the antithesis of what I negatively term "digital", as the midrange and lower treble made me appreciate Ravel's attention to form and craftsmanship while disregarding the buttoned-up approach of the romantic composers a bit father East. His sonic brushstrokes using the winds and strings sounded voluptuous, as he surely intended.



As I emphasized earlier, regular CDs sounded amazing through the Nagra Tube DAC. How amazing? There were more than a few times during the review period while playing a file through the Tube DAC / PSU combination I instinctively got out of my listening seat to flip the LP over to side two, but then realizing that I was playing a file through the USB port of my music server connected to the Nagra Tube DAC's USB input. I don't remember which album it was when that happened, but it could easily have been when I was playing Atomic Rooster's album Death Walks Behind You.

The British band's second and most successful album was released in 1970. Many fellow hard-rock aficionados remember this band, but they are not a household name, even those living in the UK. But they had two tracks that charted, one of them, "Tomorrow Night", is from this album, on the charts for 12 weeks, reaching as high as number 11. Even though I suggested that they are a relatively obscure band, they are remembered by some progressive rock fans because in their ever-changing lineup drummer Carl Palmer, later of the band Emerson, Lake & Palmer, played on their 1st album.

When playing this album, I had no intention of using it as a musical example in this review. But when the first track began, bandleader and keyboardist Vince Crane starts off the track with piano, and I nearly fell off my listening seat it was so realistic sounding. The band enters, it doesn't have a very memorable melody, but it has a certain groove that I bet was "danceable" in its day. The way the Nagra Tube DAC was able to dig into the sound of the tune, and also take advantage of its vintage multi-track sound, as I was normally accustomed to spinning my German LP pressing on Philips, half expecting to hear the occasional crackle from my ancient copy.

I realize that this description is a bit obtuse, but it was quite remarkable how little "digital" sound came through this plain vanilla 16-bit recording. Rather than slightly boost the upper midrange, it sounded more like the LP, a bit scooped out in that region, letting me listen to the entire album with zero listening fatigue.



I listened to the Mobile Fidelity Sound Labs DSD files from the Art Pepper compilation album ...The Way It Was! On the Hammerstein and Kern standard "All the Things You Are", recorded in early-stereo from 1956, at one point in the song, Art Pepper on alto sax and Wayne Marsh on tenor sax are soloing simultaneously in the left speaker. Even while soloing in tandem, they remain sonically separated, even though both instruments occupied only a small area in the faux soundstage. Gary Frommer's drums and Ronnie Ball's piano both share the right speaker. Many listeners, including myself, sometimes find this hard panning to one speaker on jazz recording objectionable, so it makes sense that many jazz fans opt for the mono version of some albums when available. But even on this dual-mono recording, the Nagra Tube DAC rendered each instrument with such a captivating, lifelike sound that it drew me into this outstanding music.

This reminded me of hearing live jazz, where when my attention would shift from one instrument to the other and it would become a sort of meditation. I was listening intently to Ball's piano vamp on the right and slightly behind the band, then my attention turned to Frommer's drums, which were a bit low in the mix, but the recording, and thus its reproduction was still good enough to hear them very well, especially the ping of his ride cymbal and swish of the high-hat, as my toe-tapping and head-bobbing continued throughout the number. I love it when that happens!



In my system, the sound of the Nagra Tube DAC/Classic PSU was seductive. Each recording that was converted into a musical signal would draw me into the music. Each note I heard was the best I've ever heard until I heard the next note that came through my speakers.

This Nagra converter was dangerous, as I'd be listening to music long past the time I should have stopped, often keeping me up late at night listening to music long past the time I should have retired. I was also late for a few meetings on Zoom. "It wasn't my fault, I'd say", it was Pete Townshend's, as the recording of his appearance with his band The Who at Hull City Hall, February 1970 made it impossible to stop listening until the two-CD set's last track, a nine-minute version of 'We're Not Gonna Take It' was over".

Or perhaps I should blame the designers and engineers at Nagra for making such a fine piece of equipment, because it acts as a siren, tempting me to listen to one more song, one more album, one more artist, one more recording. Don't say I didn't warn you. The Nagra Tube DAC with its Classic PSU power supply will make the sound of your digital files connected to its USB port, or discs player connected to its coax input sound better than you've ever heard them before.


Nagra Tube DAC And Classic PSU Power Supply Review


I think that priced at $27,000, the Nagra Tube DAC is worth every penny. And I would also think that it is very competitively priced. That is if one already has a Nagra MPS or VFS power supply. This is because if one doesn't already have a Nagra power supply the Tube DAC / Classic PSU package, which also includes the VFS base is $46,000, and I'm not willing to call that price anything other than what it is. But, wow, is this a magnificent sounding digital-to-analog converter!

I also consider it a safe bet that any audiophile that has a system that can appreciate its sonic glory and has a pair of ears will agree with me that the Nagra Tube DAC mated with the Nagra Classic PSU is a very high-performance audio component. It is also one that demands that I politely request that if one purchases the $46,000 Nagra DAC package, or even the $27,000 Tube DAC sans Classic PSU, they donate to a deserving charity. If one cannot find a worthy charity, I will be glad to suggest one. I very highly recommend the Nagra Tube DAC/Classic PSU package (or the Nagra Tube DAC if one already owns a Nagra power supply) to all audiophiles who can afford it. Absolutely!




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: High resolution digital to analog converter
Internal Processing: 11.2 MHz @ 72 Bits
Compatible Digital Formats: PCM 24 bits up to 384 kHz, DXD, and DSD 256
Bandwidth: PCM 24 bits up to 384 kHz, DXD, and DSD 256
Noise Level: -128 dBr (linear)
Inter-Channel Phase: <0.5 at 20 kHz
Distortion: < 0.02% (at -20dBFS)
Digital Inputs: Two S/DIF, AES/EBU, TosLink Optical, Audio USB (mode 2), and I2S (Nagra format)
Outputs: Unbalanced RCA and balanced XLR (symmetrical on transformers optional)
Dimensions: 12" x 13.7" x 3" (WxDxH)
Weight: 15.4 lbs.
Price: If purchased separately - Tube DAC $27,000, Classic PSU $16,000, VFS Classic $2500 
Package that includes Tube DAC, Classic PSC, and VFS Classic $43,000




Company Information
Nagra Audio Technology Switzerland, SA
Chemin de l'Orio 30A
1032 Romanel-sur-Lausanne

Voice / Fax: +41 21 643 7240
Website: NagraAudio.com



Sales & Marketing Manager USA And Canada
Rene Laflamme
Voice: (514) 826-4825
E-mail: rene.laflamme@nagraaudio.com

















































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