Digital Drive: REVIEW: Audio Note DAC Kit 1.2 DAC Processors by s.hum

Model:	DAC Kit 1.2
Category:	DAC Processors
Suggested Retail Price:	$1099
Description:	1X oversampling tubed DAC
Manufacturer URL:	Audio Note
Manufacturer URL:	Audio Note

Review by s.hum ( A ) on April 01, 2002 at 13:17:30
IP Address: 206.47.0.172

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- Pre-amble: Enhanced AN DAC1.2 -
When it came time to consider my DAC options, high on my list was the tweak-ability of the unit. This led down to the ART D/IO and the Audio Note DAC1.x kit series. In the end, the non-oversampling approach of the AN, its roomy layout and chassis, and valve analogue output stage became the deciding factors in spite of the cost differential favouring the ART D/IO - the simplicity of concept and design resonated with my approach to audio.
The transport would remain my Vecteur L-4, a CDP which is essentially an enhanced D-2 transport with an added onboard DAC. I have had that unit for a year and like it a lot. So much so, as I built the kit, listening to the unit closely as a baseline, I kept remarking to myself that this was one heck of a fine CDP, wondering if I would miss it.
I built the kit with the recommended upgrades: tantalum resistors, Black Gate caps, copper PIO caps and silver coax signal wire. In hindsight, I might have built the kit stock first to establish an upgrade baseline but as by the time I was able to get around to building it - darned day job keeps getting in the way! - I had all my parts together, so it was full bore with an enhanced DAC1.2.
- The Kit -
The AN DAC1.2 kit is a fun build. Board layout is very nice with ample room all around. The chassis is deep which some may find problematic using the stock feet if their audio shelf isn't deep enough - I'd recommend better isolation anyway with cones or Point Pods which would eliminate this problem. The unit build is very high quality with an elegant brushed aluminum 1/4" thick faceplate. Very nice and robust - the chassis is heavy gauge steel in powder coat black.
The kit can be built in an evening for the determined but I assembled it in an enjoyable and relaxed fashion over three evenings - chassis and analogue board; power supply board; hook-up wiring and final assembly. The manual doesn't have any assembly pics but it is very well written. Because the design is inherently simple, assembly is not complex. A simple pre-read of the assembly sections before proceeding is all one should need.
The digital board is pre-assembled so the only thing that needed to be done there was to remove and replace a few of the resistors in the signal path with some tantalums.
- Burn-In -
I was told that the unit should burn in for a week solid before serious evaluation but that even new it should sound pretty good. Well... maybe if your existing CDP was wanting to begin with. As I said, the Vecteur L-4 is one very good unit and it trounced the newly built AN DAC1.2 ...even after a week of 7x24 burn in. The sound was confined, lifeless, bass was lacking - not impressed. No problem, I am used to agonizing burn in times but the sluggish improvement of the AN had me wondering a few times as to whether it would indeed best the Vecteur.
200 hours later... 300... At 350 it was better but certainly did not slay the Vecteur still which for the money I would have expected. So... I swapped out the silver digital IC I was using and swapped in a JPS Superconductor digital IC. More possibilities here - possibly because I have a predisposition towards the dark sound of JPS cables which I use in my system - and after 100 hours of short burn in for the Superconductor, the AN was beginning to take notice.
Finally at 500 hours the unit shifted into high gear - night and day, the music that was coming out was engaging me again. Damn those Black gates or whatever take a long time to burn in. I'm hitting 600 hours burn in and still it seems that it is continuing to open up. I wouldn't be surprised if several more 100's of hours are required - but worth the wait!
- Wire Tweaks -
An inmate recommended that I replace the hook up wire with Continuous Cast Copper wire (CCC). Am I glad I heeded that advice! I braided up some Litz wire with the stuff and replaced all the hookup wire in the kit. After 2 days of burn in, the unit is jaw dropping in clarity and bass extension and detail, everything. Anyone who has upgraded their DAC1.x's and not done so to the hookup wiring is probably not realizing the full potential of their better passive components. Highly recommended.
I believe in feeding the cleanest power you can - digital especially. ESP PowerPro cords worked amazing with my Vecteur, so I replaced the IEC cord with one for the AN.
- Results -
I've had the Vecteur hooked up directly a few times since - when I've had the AN out for some poking around (such as the wire tweak above). It's still a nice unit (the Vecteur's in-built DAC) but no longer a match for the AN. The AN does all the things one would expect a good DAC to do - more inner detail, more bass, more refined mids and highs, better imaging and soundstage.
Yes, it does all those things BUT it's the AN's tonality and rhythm that is so outstanding. It is simply more real - transients sparkle with clarity rather than sound like edgy digital hash. A lot of what I notice isn't so much that it wasn't present before (from the Vecteur) but that the tonality is so much more correct that I find myself wakening to it in the music. It is a complete package of improvement in every parameter with more transparency and resolution while retaining emotional rhythm and flow - the increased low level detail here does not detract or interrupt the musical experience. Even in lesser recordings or masterings, I find myself toe tapping and being engaged in the musicality of the material. Given a decent mastering and I don't feel wanting for anything more - no angst over the future hi-rez here: give me more CD's!
Whereas, sometimes I have mused about tackling the integration issues of adding a sub to my 1.6's, no longer. The bass out of the AN is not only prodigious but incredibly resolved and detailed - with that correct tonality again which I can't emphasize enough. Dynamics are simply more alive, more real. Add the valve midrange and highs (absence of any digital artifacts) to lust for (oh, the vocals... so seductive!), and the engaging musicality of the AN, and I am a very happy camper indeed these days.
- Caveats -
The AN DAC is susceptible to microphonic vibrations. This can be audibly heard by tapping the chassis, whose sounds will add themselves to whatever is coming out your speakers. This should not be a problem if you've already addressed the mechanical isolation of the unit with cones or Point Pods or the like as a result of needing to stand the unit on a shelf that is not as deep as the chassis.
One minor fault - and it is a minor one - which is buried by the enormous qualities this DAC brings: there is a very slight low level transformer hum present which can be heard near the speakers. Depending on the size of your room, normal listening volume, system, etc - this may or may not be noticeable. On the stillest of nights one might be able to detect this ever so faintly (above zero ambient noise levels!) from one's listening position when no source material is playing - if you listen for it to aggravate yourself! The simplest solution is to get lost in the music!
Yeah, I'll probably try to resolve that hum somehow as a DIY exercise - anyone wishing to share their AN I/V transformer upgrade can get my attention as an alternate solution! For now though, my next goal is to break my next redbook CD collection milestone!
If you are considering a DAC, kit or pre-built, the Audio Note DAC design and approach is for real. I, for one, can revel in the fact that so many existing classical and jazz issues are available for my enjoyment.

Product Weakness: Slight transformer hum.
Product Strengths: Tonality, musicality. Inner detail and clarity. Dynamics and smoothness. Build quality.

Associated Equipment for this Review:
Amplifier:	Audiomat Arpege (Integrated)
Preamplifier (or None if Integrated):	None
Sources (CDP/Turntable):	Vecteur L-4
Speakers:	Modded Magneplanar 1.6's
Cables/Interconnects:	JPS Superconductor IC's and JPS Ultra speaker cables
Music Used (Genre/Selections):	Classical, Jazz
Room Size (LxWxH):	13 x 21 x 8.5
Room Comments/Treatments:	DIY Room lenses; carpeted and furnished living room
Time Period/Length of Audition:	4 weeks
Other (Power Conditioner etc.):	ESP Power Disributor and Cords
Type of Audition/Review:	Product Owner

Product Weakness:	Slight transformer hum.
Product Strengths:	Tonality, musicality. Inner detail and clarity. Dynamics and smoothness. Build quality.