Review: Accustic Arts Reference Tube Hybrid DAC II DA converter


Category: Digital

This will be my third go around reviewing a DAC from the German company Accustic Arts. In between having the MK-3, MK-4, and now their Reference Tube Hybrid as my digital front end, I have had the pleasure to auditioned many of the highest regarded DACS and CDPS in the last couple of years. Many of this digital pieces offered great performance, a few were sonic "turkeys" regardless of some steller reviews, but based on great performance without having to get a second morgage to purchase it, I keep coming back to Accustic Arts.

The MK-4 was a significant improvement over the MK-3 and I still believe it's one of the finer sounding DACS around today. That's way I was skeptical about how much better/different would Accustic Arts new "baby" would be compared with their older DAC.

As in all my reviews I do not get into specifications, you can go to Accustic Arts website to get the details, but always comment on build quality and physical appearance. Like its older siblings the Tube Hybrid is just beautifully built and really is "eye candy". The German engineering and craftmanship is very easy to admire. I know one important technical aspect that this is the first DAC in the world that does not use tubes in the analog section, but somewhere further upstream when bits are still bits before the analog conversion stage. What the tubes are doing and how they are used in the overall design circuitry I don't have the foggist notion, just that sonic bliss is taking place.

When I discovered that Accustic Arts new reference would use tubes I was somewhat concerned for the following reasons: 1) My past experience with tube based DACS, such as the Zanden and a very high level Audio Note, was that they offered a very wonderful midrange but they lacked macrodynamics and extension on both the top and bottom ends. 2) The transparency/clarity and very small details I love in the overall sonic perspective of my system were lost.

SONIC PERFORMANCE

I do not like to result to sonic cliches to describe the sonics of a piece I'm reviewing, but this DAC is a "killer"! I hope all of us can agree that once you get to a high level of excellence in audio gear, their are many great pieces and differences become more quantitive then qualitative. We also have to factor in personnal taste and system synergy in to the equation. Taking all of this into account let me try to explain way this is the best digital I have heard in my system to the present time.

1) The Tube Hybrid retains all of the transparence/clarity and microdetails of the MK-4.

2) I will not say that the Tube Hybrid's extension on the top and bottom are better then the MK-4, but the the overall slam and dynamics is slightly more "lively" and natural sounding. Remember, the MK-4 was no slouch in these sonic areas to begin with.

3) Now we get into the specifics of why the Tube Hybrid is a "killer" in qualitative terms.

A) Unlike adding a "warm/euphonic" aspect to the music this DAC adds what many would call a touch of "bloom/fullness" without destroying the overall linear cohesiveness of the sonic perspective. Another more concrete way of saying it would be that image density and the overall harmonic structure ( leading edge, body, and decay trails) is more natural or what alot of audiophiles would dscribe as "analog" sounding.

B) This DAC offers an overall more sense of liquidity and smoothness, but not at the expensive of slam/punch/dynamics or sounding "soft" to be pleasing to the listener.

C) I have a hunch that another reason why the Tube Hybrid sounds more "real" is that it is more tonally linear compared to the MK-4, and any other digital piece I have heard on Redbook, which makes it sound of one piece top to bottom.

D) The Tube Hybrid offers the most natural timbres I have ever gotten from a digital front end.

E) I don't believe that my system's overall soundstage dramatically improved with the Tube Hybrid, the MK-4 was a champ in this area, but the layering and the air around players also went to a qualitatively higher level.

When I wrote a review here on the GON on the Stealth Metacarbon IC's I struggled to use words to describe the sound of "nothing", meaning these cables just get out of the way of the music so the illusion of real music being played by real people just gets spills into your mind and gut. Well, this DAC hits my sonic ear's the same way, it just sounds more like real music then I have ever heard in my listening room before. The Tube Hybrid sonics can be broken down into specifics, as I have tried to do, but its the overall natural/easy/lifelike sonic illusion without the loss of details,prat,sparkle that makes this a very special piece indeed.

I always end all my reviews with the statement their is no "BEST" in high end audio, but many fine pieces along with the factors of personal taste and system synergy. The new Accustic Arts Tube Hybrid DAC II is among one of the finest DACS on the market today, and while it is not inexpensive it competes with DACS triple its price. This German company sure has some talented thinkers with great ears when it comes to digital gear. If your in the market I highly recommend you audition this DAC before you purchase another.

Associated gear
Click to view my Virtual System
teajay
In the current issue of Sterophile (June 2008) there is a review of the Cabasse La Sphere speakers, which do a fair amount of digital processing. Analog signals are digitized at 48kHz which let to the Author's comment: "A lot of processing goes on within the Sphere system, and unless CD is your only source, 48kHz is a barely sufficient sampling rate. With the exception of vocal sibilants, this processing wasn't grossly audible per se, but it certainly affected the system's ability to sound real, as opposed to sounding really great."

I realize that the AA DAC is not digitizing analog sources, but it's not the first time that I heard the notion that 48kHz is barely sufficient, which leads me back to the original question.
Understand, on the other hand I have a few very, very well recorded 16-bit 44.1Khz RBCDs that puts the majority of recordings, including most SACDs, out there to shame...

I think the sampling question is a relevant one, but it shouldn't be taken out of the context of the whole recording and reproduction chain, its IMHO a smaller part of the overall performance. Maybe in an all digital system its more important though, like what you mentioned above.

At least my CDSA DAC's ability to upsample to 5.6Mhz did not lead to a better musicality vs the AA Tube DAC II on the same music. Maybe I liked the tube coloring ... who knows

Just my 2 cents.
Last week I replaced my AA Drive MK11 with a MBL 1521a transport. I was expecting a difference, but frankly was very surprized, happly so, with the significant improvement across the sonic landscape.

1 A larger soundstage with more air between the players.

2)A much greater ease/liquidity without lose of dynamics or slam.

3)Extension on the bottom end with more power and speed. I believe its the best bass I have ever had in my system.

4)Microdetails are more apparent but in a very natural way, I believe I'm hearing more because this transport has a much lower noise floor then the AA Drive MK11.

I would say the musical/enjoyment level using the MBL transport with the AA Reference Tube Hybrid DAC went up another 25% or 30% in my system. I still believe that the AA Tube Hybrid DAC is one of the best sounding digital pieces on the market today and when you factor in its cost compared to what it competes with sonicly, kinda of a bargain. I have no idea if the new AA reference transport will perform better/different then the MBL transport, but either way it shows two things; 1) Transports really can make a difference 2) How much more potential performance can be gotten out of this terrific DAC.
Teajay, what digital interconnect(s) are you using between the Transport and DAC and from the DAC to your pre? Have you experimented at all with this and are you using any isolation under both?
Post OBO hotbird,

Differences between Accustic Arts Ref Drive2 and Drive Mk2

Drive Mk2 : CDM Pro 2 LF – drive module with cast metal frame and involved mechanical decoupling
Ref Drive2: CDM Pro 2 LF – drive module with heavy die cast metal frame and involved mechanical decoupling, embedded in a massive aluminium housing (subchassis-construction principle)

Drive Mk2 : Generously dimensioned magnetically shielded toroidal core transformer (75 VA)
Ref Drive2: Two generously dimensioned & magnetically shielded toroidal core transformer of premium quality (2 x 75VA)

Drive Mk 2: Optimum smoothing thanks to 45,000 µF power supply capacity
Ref Drive2: Very high power supply capacity (61,000 µF) for perfect power supply.

Drive Mk 2: Resonance minimising aluminium housing
Ref Drive2: Extremely stable, massive and resonance optimized housing, primarily made of 10mm aluminium plates, ultra stable and acoustically damped top load cover

Weight
Drive Mk 2: 15kg (35lbs)
Ref Drive2: 18kg (40libs)

Unique to Ref Drive2 only
1) Integrated, specially designed Accustic Arts™ line filter for perfect and extremely clean power supply (line filter switchable)
2) Polarity switch for correct phase of the mains voltage

Unique to Drive Mk2
Drawer with indirect blue lighting for Accustic Arts logo feature (lighting can be switched off)