Review: Scott-Nixon Tube DAC, upgrade parts DA converter

Category: Digital

I'll cut to the chase for those who hate long reviews, opinions and posts. I've not been so excited, so... *UP* on an audio product since I rebuilt my first tube amps over 15 years ago, salvaged Dynaco MK III's with good Genelex KT88's on board. This little black box has transformed my CD collection of hundreds and hundreds of discs. Of all those, I had, at most, a selection of 20 or 30 favorites. Of these, one or two that might find their way to the transport's tray on any given day. After the DAC had burned in for a few days, things got really nice. I would say that my desire to listen to only 10 or 20% of my CD collection has gone to an estimated 80 or 90%. I began going through CD's to simply test the sound of this DAC against my other two DAC's and upsamplers, a CAL Sigma II 24/96, Assemblage D2D upsampler and an MSB III with upsampler. It wasn't long before I decided to sell all my other redbook gear. So out went the CAL Sigma II with 24/96 chip and Assemblage D2D-1 processor/upsampler. The MSB III may stay to translate DVD video and audio.

The CD tests bogged down as I found myself sitting and listening to whole CD's through the scott-nixon. In comparison, the CAL Sigma II had a pleasant but forward sound that was, for the most part, bland, inoffensive. Even more so when upsampled through the Assemblage. Not irritating, just no that musically involving. The MSB III gave more of the same with or without the upsampler engaged, except it wasn't as forward in it's presentation as the CAL. I have grown used to these DAC's and consciously had accepted that this was as good as redbook CD was going to get (at least on my budget) but unconsciously I was still hungry. So for Christmas I bought myself the scott-nixon DAC. With the scott-nixon DAC in place, things turned upside down for sure. All of a sudden there was much more life to the music. Toe tappin', *I didn't know this CD was this good*, musically involving sparkle and excitement. The music didn't just play in front of or between the speakers any more but I was presented with a larger, more lively, more open sound with a real sense of depth. This DAC couldn't save really bad recordings any more than a super phono setup can save poorly recorded records. But, it has proven to me that much more of my CD collection is worth listening to than I had ever imagined. Certain music with piano or flute, two instruments hard to get right in my head through digital, finally came through fine or at least much more acceptable.

I will stop here with the *reviewer speak* type lingo and tell you what happened the other night. I had spent most of the previous listening and enjoying CD's. My wife came home after working a long shift and crashed on the couch. Julia Fordham's CD, Porcelain, was playing. My wife sat there and listened a while and finally commented, "She sure has a beautiful voice. Who is she?". I just snickered to myself. I've owned and played this CD for over 10 years and my wife had never "heard" it before. Heard it done right that is, the way this new DAC translates it.

The scott-nixon DAC version I chose was his most expensive tube DAC. $475. There are versions from blank boards to no tube output to the version I bought. Besides the Ack! dAck, I know of no other competition except for DIY projects under $1000. I do know that Audio Note, 47 labs and a few others offer the same basic concept for $1200 to $50,000. But I'm thinking there are some serious diminishing returns here. Even if there are improvements at all!. I was very skeptical when I first started reading about the 0 oversampling concept. It just seemed the biggest draw was, they were easy to build for the more DIY adept. But finally, I took the plunge and am glad I did. Redbook CD's may be all I'll ever need or want. Especially when you think what it costs to get into SACD, THEN try and make it sound *just right*. Another uphill, money sucking climb, IMO. jim...

Associated gear
Home made linestage based on Alan Kimmel's design and my power supply design. No electrolytics or resistors in the PS. Home made tube mono amps with 6SN7 long tailed pair front end. Genelex KT-66 output tubes. JM labs Daline 3.1 speakers. IC and speaker cable are continous cast copper. Pioneer DV-434, modified, tweaked as the transport.

Similar products
MSB III, with upsampler
CAL Sigma II, 24/96 upgrade
Assemblage D2D upsampler
Thanks for the review, I've almost pulled the trigger on the Nixon DAC a couple of times. Your review was a big help and I may give one a listen in my system soon.

Thanks for your review. Wondering if anyone here had the opportunity to compare Scott-Nixion to Channel Island VDA-1 DAC. The VDA-1 is another very samll, inexpensive and well regarded unit, or at least according some postings at A'gon.
Scott refurbished my vintage, tube output, Anodyne ATAS to better than new status, and even his decade old design still sounds amazingly natural, musical, and free of digital listener fatigue. His website,, points out that his latest minimalist, purist DAC's outperform his past work. And with the new product line priced so low, certainly worth considering. His baseline DAC lists for $250, assembled, just impossible to believe how much performance can be had for less than the price of many high quality digital interconnects. Apparently, Scott's $475 TubeDac+ model purchased by Diyaudio is well worth the extra money, if it can induce such an outpouring of love.
I would highly recommend Scott's upgraded power supply, the 3XAC, it will add even more punch and bass.

Have you tried different tubes yet? I have settled on a cryoed Brimar CV5358.

I have to laugh at myself, because the power cord I'm using cost me more than the DAC, lol

John C.
I, too, am thinking about this one. Actually an waiting for one to be shipped.
Question about the power supply: what is the difference between 3XAC and 3XDC, or 3XAC and the "desktop transformer"? Website info is not clear about it. Desktop transformer is 4A while 3XAC is 3A. I have emailed Scott, but he seems busy making my Tube DAC+...

Yeah, power cord or IC will definitely cost me more than the DAC for me, too...
The 3XAC is a 12 volt 3 amp AC toroidal transformer with plug in for designer AC cables. For the tube DAC and SARU DAC

The "desktop transformer" is a 12 volt AC 4 amp *normal* trasformer. For the tube DAC and SARU DAC

The 3XDC is for the regular DacKit and is a 12 volt DC pre-regulated supply. So remember some run on DC and some on AC transformers. I doubt he would sell someone the wrong one jim...
To Hotsauce, I'm running an Amperex. I would guesss being used as a cathode follower with no voltage gain, there won't be much of a sound difference but I'll try others (IF) I ever get bored. Stick with 6DJ8's proper though. Something *almost* like a 6DJ8 that pulls too much filiment current might burn up the circuit. I think he says this on the web site. jim...
I too love the Scott Nixon TUBEDAC+. It replaced a cj Premier 9, which replaced a Cary 308, which replaced a Sony SACD 777ES, which replaced an AH!Tjoeb 99. The Scott Nixon is is far above all these others, with or without a high quality transport.
Diyaudio: thanks. I asked Scott to add 3xac to my order, in diecast box! Have you had chance to shoot out with dAck! yet?
Hello Khokugo, The scott-nixon/dAck! Shootout has been put on hold for about two more weeks. I'll go out on a limb and say the scott-nixon DAC is the one for me and my personal tastes. I have two tube systems in house. There may be reasons others will choose the dAck! As a matter of fact, I've already ordered a second scott-nixon for my second system. This one with the 3xac upgrade. jim...
Has anyone heard the TubeDAC against the "tubed" all-in-one machines out there - the Jolida JD-100, the Ah! Njoe Tjoeb 4000, the Heart CD6000, or the Shanling T-100 or 200? I'd be REALLY curious to see how folks feel it fairs against any of these machines - and why. Thanks in advance!