March 2020

Audio Research DAC9 Digital-To-Analog Converter (DAC) Review
An organic sound that draws you into the music.
Review By Tom Lyle

  This past summer I was in a showroom auditioning a new line of speakers that included a system that was made up of mostly Audio Research components. Even though I heard four other products from that same line of speakers that day, it was their smallest model that impressed me the most. As it just so happens, this system included the Audio Research DAC9 digital-to-analog converter that is the focus of this review.

I heard Audio Research's DAC9 within other systems that day, too, and I was so impressed that the next day I sent a request to obtain a review sample. Those who know me are aware that I'm mostly an analog kind of guy, and to have a music epiphany that included a digital component surprised me. Although the DAC9 had already been on the market for a while, the part of my brain that controls, or at least tries to control, my audiophile fantasies that included a picture of this converter in my system, auditioning it for review.

The problem was that Audio Research's DAC9 is a very popular component. I had to wait a while before a sample was available for me to review, which wasn't until the winter of 2019. As they say, good things come to those who wait.

Series
The DAC9 converter is from Audio Research's latest Foundation series, which was created by the same team that was responsible for their Reference Series, which I never heard, but read many, many positive reviews, and just about every audiophile I've ever had contact with that had any experience with a Reference Series components speak of it as if it had some sort of supernatural powers. Audio Research's DAC9 has a vacuum tube analog section that uses a pair of 6H30 tubes, and this combined with the company's latest digital design that can decode DSD, plus PCM files up to 384kHz according to Audio Research. It does this with superior musicality.

Audio Research designed two separate data paths to the DAC9's converters, one for the PCM files that can decode the signals up to 384kHz sample rates, and the other to handle serial DSD files at 1x and 2x DSD clock rates. This ensures that the conversion of the signal is free of distortion errors, and which pretty much guarantees "sonic purity". The DAC9's PCM native sample rate is upsampled to 384kHz, and there are also selectable digital filters available for all the incoming digital signals.

The DAC9 has an asynchronous USB input, which I used for most of the review period, with four other "galvanically isolated" inputs including, RCA (coax), BNC, AES/EBU, and TosLink. Audio Research claims that they pioneered implementing quad D-A converters with each channel using dual stereo DACs running in mono and provides a balanced digital signal. They say that this architecture increases the component's dynamic range and at the same time lowers the noise floor.

Looks
What may appeal to many audiophiles is the fact that this Audio Research component looks very much like an Audio Research component. Even though the DAC9 is also available with a black finish, to me, the archetypal Audio Research component has a silver finish. Regardless of the cabinet's finish, critical to its appearance are the large handles on either side of its front panel. To my surprise, the DAC9 only weighs only 14 pounds, making these handles for the most part decorative, although the handles did make it a little easier to carry it and set it up on my equipment rack.

Below its easy to read vacuum fluorescent display on the front panel are 6 push-buttons – power on/off, menu, option (used with a menu), enter (used with a menu), input, and mute.

The DAC9's remote also has all the front panel controls, along with six controls that are accessible only with the remote. The first one of these is its "Hours" button, which displays the total accumulated hours of operation. This can come in handy because Audio Research recommends changing the vacuum tubes after their approximate 4,000-hour life-span, so this display will count these hours off for the user. On the remote is also the "Input" selector, a "Display Brightness" adjustment, "Upsampling" (for PCM signals), "Invert", so absolute phase can be switched between 'normal' (in-phase) and 'invert' (180° inversion), and "Filter" (fast and slow).

The DAC9 is a full-function, modern DAC. It is certainly nice that the DAC9 digital-to-analog converter decodes most current formats with "state-of-the-art vacuum tube technology", but to me, the manufacturer can tout any design elements it wishes, but the most important thing about any component will end up being its sound quality.

Arrived
As soon as the DAC9 arrived at my doorstep I unboxed it and set it up in my system. I placed the DAC9 on my Arcici Suspense equipment rack, which replaced my solid-state reference, the EMM DA2 converter. I connected a USB cable from my computer-based music server's USB output. On my music server, I use both Foobar2000 and J. River Media Center software to play music files that are stored on hard-drives, which are also accessible through my home network. I also had on hand an OPPO UDP-203 Blu-Ray/universal disc player to spin the occasional 5-inch silver disc, the player's digital coax output connected to the RCA coax input on the DAC9's rear panel.

I connected the DAC9's analog output to the Nagra Classic Preamp, which was connected to the Pass Laboratories X250.8 power amplifier. The amp's speaker outputs were connected to a pair of Sound Lab Majestic 545 electrostatic speakers. Even though Sound Lab claims that these speakers are full-range (their specifications say that they reach to 32 Hz (+/-3dB) in the bass), I augmented them with two SVSound SB16-Ultra subwoofers that each has a single 16" driver, an internal power amp that puts out 1500 Watts, and is rated to a subsonic 16 Hz (+/-3dB).

The speaker cable, USB cable, digital cable, and all the interconnects in the system were made by Kimber Kable, which I reviewed at the end of last year, their Carbon 8 interconnects, Carbon 18 XL speaker cables, Ascent power cables, and Select Copper USB cable. Speaking of power cables, the listening room has two dedicated power lines that run straight to our home's circuit box in the basement. However, much of the front-end equipment uses a battery power supply, the Goal Zero's Yeti 400, while the power amp uses a separate, more powerful batter power supply, the Goal Zero Yeti 1000. I only use the power amplifier's battery power during the daylight hours, other times the power amp is plugged directly into the wall receptacle made by Virtual Dynamics. Even with the battery power supplies, there were still some more power cables, such as those coming from the subwoofers that were connected to a Chang Lightspeed ISO 9300 power supply that was plugged into the wall outlet.

The listening room has acoustic treatment panels on its side, back, and front walls, as well as LP shelves throughout. Commercial-grade carpeting covers the floors, and the walls are painted with Sherwin Williams "Sky Fall" blue indoor acrylic-latex. Psychology Today says "the color blue affects us both cognitively and affectively making us feel more comfortable".

Understanding
Now that you know all about the system in which this digital converter was used, I hope this will lead to a greater understanding of any sonic descriptions I will use in this review. My system is very revealing, even though it isn't an esoteric one, but still, I think it is more than good enough to appreciate the sound of the Audio Research DAC9, and also let me hear the nuances that differentiate this digital converter from others.

The Audio Research DAC9 costs $8500. After my showroom audition I was surprised! I expected it to cost much, much more. I still wanted to hear it within my system. As my reference DAC costs a little more than three times as much, I was expecting this Audio Research converter to sound good, but not as good as the converter that I was using daily. And, that is one of the reasons why I was practically floored when I first played some music through the Audio Research DAC9.

What I heard when playing music through the Audio Research DAC9 was a sound that distinguished itself from my reference, not in huge night versus day, yin versus yang sort of way, but there was a large enough difference that I don't think it would take an audiophile with trained ears to hear the difference between the two. Still, there was not a huge difference between the two, and that is one of the reasons why I stated above that I was so surprised.

I played the DSD file of Mahler's Symphony No. 2 "Resurrection" with David Zinman conducting Zurich's Tonhalle Orchestra I was amazed that the Audio Research DAC9 could make me not only forget that I wasn't listening to my reference converter, and at the same time sound so good that it reminded me of the times I heard this piece played live. There wasn't a time that I was listening to the DAC9 when I would think to myself that this DAC couldn't handle any of the many complex passages that are in Mahler's complex masterpiece. Compared to my reference I think that the female soloists might have sounded even better than my reference! The midrange of the DAC9 was its strong point, and I think that when the female vocal soloists entered, in this case, Julianne Banse, and especially when Swedish contralto Anna Larsson sang their parts in the fourth movement, it was as if the DAC9 was purposely taking advantage of my speaker's midrange prowess. Reality occasionally showed its face, as a huge stage in a large hall with a gigantic orchestra on its stage in nothing that will ever be able to be replicated in my listening room.

Yet the DAC9 was able to capture the gestalt of Mahler's overly long and exhausting piece, despite this not being the greatest performance of Mahler's Resurrection in my collection. However, its sound quality might be one of the best in my collection. I love it when I have everything dialed in, and my system can transport me to the original event. This symphony is one that I've always loved, as its a tour of Mahler's neurosis, as the piece is full of funeral music and many orchestral complexities. During this listening session, the DAC9 made me also realize that I was hearing one of the best string sections I've ever heard captured with a bunch of microphones and a DSD recorder.

On this masterpiece, the DAC9 demonstrated that its bass response was excellent, its upper treble, too, was excellent. Mentioning that these traits weren't as good as my reference isn't the point here, even though there was a scintilla of softening in the frequency extremes. I bet there are likely many audiophiles who would be willing to trade-in the ultimate in frequency extension for these organic sounding frequencies that the DAC9 delivered to my preamplifier. But, also for a midrange that is practically unbeatable at any price. The tubes in this unit are what is at least partially providing the listener with a sound that draws one into the music that will eventually be emitted from their speakers.

Audio Research's DAC9's rendering of the vocals and string sound was second to none, as the bass, upper winds and cymbals were not only stripped of any stealth digital nasties, but these instruments and vocals were brought into my listening room as for all intents and purposes real-sounding instruments and voices, to the extent that any high-end audio system can. No, my reference DAC's treble does not sound like it has any digital artifacts in its treble. It does expose any of these types of sounds that may be lurking in the background due to the recording it is processing.

It's no secret that I've been listening to lots of types of music that make up the genre that is called metal for at least the last couple of decades. More than ever, young rock musicians choosing this genre over all others. I've been told by many who practice this art that they do so because it lets them use as many of the technical skills on their instruments that they've acquired over the years, and perhaps even more than this, they are in love with the volume and distortion that the band Black Sabbath conceived in the late 1960s that they can bring into countless modern sub-genres.

There is a band from Montreal formed in the early 1980s named Voivod that plays metal with overtones of punk, progressive rock's unusual time signatures and atonal guitar chords with plenty of tri-tones. Their lyrics are influenced by post-apocalyptic literature, politics and science fiction. I know, on paper this might sound weird, but in actuality, this band is very engaging. Most of their fans consider Voivod to be part of the progressive-metal sub-genre. That they are still releasing records to this day, despite the death of their original guitarist in 2005 is a testament to their appeal.

One of their recent albums, Target Earth, from 2013 is one I've been listening to often, a plain vanilla 16-bit/44.1kHz file I play through my music server via Foobar 2000. The complex arrangements of their songs make for a good test of a high-end audio system, but especially the converter that along with my power amplifier seems to me to be the component that is doing the heavy lifting (pun not intended). Even though the addition of reverb to the vocals that make it seem as if he's performing in an arena, it sounds like for the most part the instruments are recorded with very little signal processing. The drums pound, the bass guitar growls, and the guitar sounds as if it might damage one's speakers if turned up too loud. These are all positives when considering what makes a good sounding metal album.

Despite the reverb added to the vocals, the Audio Research DAC9 places them apart from the din of the raging band, on a recording that seemed to occupy every frequency that my speakers can reproduce. The vocals were still clearly audible, and if I preferred to pay attention to the lyrics rather than the rest of the band, I could easily do so. The DAC9 had no problem separating the instruments in its large soundstage, and so, as I did with the vocals, I could follow each one if I wanted. The DAC9's overall transparency drew me into the music, and honestly, it made it more difficult to analyze its sound for reviewing purposes when attempting to listen to the barrage of music at the same time. This album is a great recording that uses stereo imaging not only by simply placing of instruments and voice in the left or right channels, but using digital processing to fill the soundstage by multiplying the guitars with delay, and then routing the delayed signal to both channels.

With all this going on, it was still tough to miss the DAC9's ability to project a vast soundstage between, around, and behind the speakers. The background vocals added to the huge soundstage with engineering and mixing techniques beyond my understanding, with the lead vocals centered between the speakers as if it was a three-channel recording… and system with a center speaker. Imaging was also provided via the drums in a big way – its' ride cymbal locked in space as the crash cymbals exploded into an expanding space around the speakers and throughout the soundstage. Listening to this album through the Audio Research was a blast. Literally.

Review
I'm sorry I haven't reviewed the Audio Research DAC9 until now, with my only excuse being that I wasn't aware of its presence until I visited World of McIntosh Townhouse to audition the latest Sonus faber speakers. The components used for one of the speakers included the DAC9, and it was obvious that its presence in this system was making a major contribution to the excellent sound I heard that day. The Audio Research DAC9 has been on the market for a while. As Audio Research is a manufacturer that doesn't replace models very often, one shouldn't hesitate in considering this converter for one's high-end audio system. This digital-to-analog converter should be considered if shopping for a converter anywhere near its price. This component should also be considered if shopping for a converter quite a bit higher than its asking price, as it can easily compete with converters costing much, much more.

The DAC9 takes advantage of its vacuum tube innards. Its midrange is its strong point. Although I commented about its slight softening of the frequency extremes, this shouldn't be taken as a pure negative, as its organic sound is one that many will be drawn to. In fact, the sound of the DAC9 is one that draws the listener into the music. It has enough power in its frequency extremes to contribute to the lifelike reproduction of all instruments regardless of where its major frequencies lie, as this is the nature of the Audio Research DAC9. It is obvious that the DAC9's raison d'ętre is music, converting signals in the most transparent way possible, at the same time the DAC9's innards somehow realize that these signals are of music. It is as if the designers of this digital-to-analog converter included sonic magic as part of its design. Recommended.

Specifications
Type: Hi-Res Audio digital-to-analog converter
Frequency Response: +/-0.15dB 20Hz – 20kHz; +/-3.0dB 6Hz – 192kHz.
THD + Noise: Less than .002% at 2V RMS 1kHz Balanced output.
Signal To Noise: >114dB.
IMD + Noise: 0.001% (SMPTE ratio)
Channel Separation: 107dB
Intrinsic Jitter: <10pS.
DAC Resolution: 24 bits.
Push Buttons: Power, Menu, Option, Enter, Input, and Mute.
Output Impedance: 500 Ohms balanced, 250 Ohms SE.
Digital Filter: Selectable Fast or Slow algorithms.
Upsampling: All Inputs upsample to 384kHz.
Inputs: USB2.0HS to 384kHz, DSD/2xDSD; RCA, BNC, XLR to 192kHz; optical to 96kHz.
Rated Output: 3.8V RMS Max Balanced; 1.9V max SE (@ 0dB input).
Power Supplies: Electronically-regulated low/high voltage supplies.
                      Line regulation better than 0.01%.
Noise: -103dB
Tube Complement: Two 6H30 dual triodes.
Dimensions: 19" x 7" x 15.5" (WxHxD)
Handles Extend 1.5" forward of the front panel.
Weight: 32.0 lbs.
Price: $8500

Company Information
Audio Research Corporation
6655 Wedgwood Road North,
Maple Grove, Minnesota 55311

Voice: (763) 577-9700
Website: www.AudioResearch.com