Gramophone Dreams

In contrast to phono cartridges and analog tape recorders, digital audio converters distinguish themselves by the fact that they can be fashioned in an almost infinite number of ways. Therefore, the odds against two manufacturers' DACs or ADCs sounding exactly the same are extremely large.

Nevertheless, I've heard countless audiophiles say that "bits are bits" and that today's digital-to-analog converters sound mostly the same. Some go as far as to declare today's DACs blameless—neutral—when debating issues of audio-system sound quality.

In my view, such opinions deny the likelihood that widely varied methods for reclocking, format conversion, oversampling, interpolation, current-to-voltage conversion, and reconstruction filtering affect the sound character of the music files being rendered.

My experience suggests that many budget DACs do sound the same: slightly blunt, unsupple, noisy, processed. A lot of DACs, no matter the type or price, make music sound processed, as if all the spinach in my cream-of-spinach soup had been chopped by a machine into pieces of exactly the same size and shape. Once I noticed this blenderization effect, I declared it a coloration.

I didn't realize it existed—this coloration—until I experienced digital without it in several of my friend's systems, all of which use expensive R–2R (or other ladder-DAC) converters made by companies like Totaldac, Denafrips, or MSB. Listening to those systems prepared me for my discovery of HoloAudio's modestly priced Spring DAC at Capital Audiofest's CanMania in 2017. The minute I heard the Spring, I knew: This $1698–$2698 DAC was recovering music via some sort of silent, un–digital-sounding channel, just like my friend's DACs.

Three years later, I am auditioning HoloAudio's newest, most expensive converter, the $3798–$4998 "May," and wondering: could this DAC sound as natural as my friend's fancy DACs?

The HoloAudio May
According to the kitsunehifi.com website (footnote 1), the new DAC's name, "May," refers to "the possibility of"—the word that means that—and not the second month of, well, "spring." I am not certain what that is meant to convey, but I do know that my transition from using HoloAudio's "Spring" as my daily driver reference DAC to using the May has opened my mind to the possibility of a more utopian digital future.

Tim Connor, of HoloAudio and KitsunéHiFi (they are the same company), calls this new, two-chassis converter "The ultra-endgame DAC." That is a pretty fantastic claim, but, based on the high levels of build and sound quality Jeff Zhu (HoloAudio's founder and chief engineer) packed into the reasonably priced Spring DAC, I believe that the May DAC is an assault on the state of the R–2R converter art.

The May DAC is a dual-mono, direct-coupled, R–2R resistor-ladder design. It is housed in a matching pair of thick-walled chassis made of black-anodized aluminum and polished copper. Its substantial (20lb) linear power supply is housed in a separate chassis, connected to the DAC-circuitry chassis by a flexible, well-constructed umbilical cord about a meter long.

Both chassis measure 17" × 12" × 2.2". Their official combined weight is 39.8lb. The May has a typical array of digital inputs: two coaxial, one optical, an AES/EBU, a USB, and two I²S over HDMI. It also has balanced (XLR) and single-ended (RCA) analog outputs. The May uses an op-amp input stage and a discrete, class-A transistor output stage.

The converter chassis runs class-A warm-to-the-touch, while the power supply chassis stays room temperature, suggesting that its resistors and four power transformers are over-spec'ed. Just after the May arrived, I tried it with the DAC on top of the power supply and heard no apparent noise. The next day, I moved the power supply chassis to a more strategic location, on the floor about 20" away.

Like the Spring, the May has been optimized for nonoversampling (NOS) use. However, it includes three front-panel–selectable oversampling modes. (Oversampling is accomplished via an AK4137 chip.) The first OS mode, labeled OS, "supersamples" PCM to higher frequency PCM and "oversamples" DSD to higher-frequency DSD. The second OS mode, designated OS PCM, converts all PCM and DSD inputs to oversampled PCM. The third OS mode is called OS DSD. It converts both PCM and DSD inputs to oversampled DSD.

The May does not include line-level preamp functions or a volume control. To my surprise, however, it did come with a heavy CNC-machined black-anodized aluminum (with copper buttons) remote control. This remote allows users to mute, change inputs, or turn off the display. There is also a Mode button, which allowed me to switch from NOS to oversampling modes—on the fly—from my listening position. I had much fun with this.

KitsunéHiFi offers the HoloAudio May DAC at three levels of parts quality:

Level 1 is the standard, two-chassis May costing $3798. It uses the same XMOS XU208 USB input module as the Spring2 and features dual O-type (not toroidal) power transformers wound with flat, 6N copper wire. The capacitors in the heavily regulated linear power supply are by Rubycon ZLH, Panasonic FC, Vishay, and Mundorf EVO silver/gold. The fuse is a Shurter Gold type.

Level 2, at $4298, adds a new, "enhanced" USB XMOS input module with the HoloAudio Titanis 2.0 circuit. KitsunéHiFi claims this new USB module is "twice as powerful/capable as the one used in the Spring2." It also adds "custom proprietary" 1000V 1µF HoloAudio branded power supply capacitors (replacing the standard Mundorf EVO silver/gold caps).

At $4998, the Level 3 KTE (Kitsuné Tuned Edition) reviewed here uses hand-selected DAC modules for "best measurements and dynamic range." After hand-selection, these DAC modules are covered with black CNC-machined copper shields emblazoned with the Kitsuné fox logo. The KTE edition replaces the standard copper hookup wire with 1.5mm pure OCC silver wire "soldered direct to the PCBs with Mundorf Supreme 9.5% silver solder." In this version, the standard Vishay caps are upgraded to KTE-brand capacitors, the standard IEC inlet connector is upgraded to a pure silver/rhodium plated Faston type, and the power fuse is upgraded to a Red Nano brand with graphene and quartz filtering materials and gold-over-silver contacts.

After reading the May KTE's parts inventory, I am sure the DAC (and cable) deniers among you are screaming "snake oil!" However, a more astute DAC consumer would have noticed that, typically, passive R–2R DACs lean heavily on specialty parts options while sigma-delta and FPGA DACs do not. Why do you think that is?

Consider this: Maybe, when the effects of oversampling, format conversion, interpolation, active signal processing, and reconstruction filters are minimized or eliminated, the sonic character of passive parts becomes easier to recognize, like low-level detail emerging from a lowered noise floor.

Intona USB 3.0 Superspeed Isolator & Impedance Controlled USB cable
Speaking of noise: I have experimented some with galvanic isolators. Off and on, I've used ifi Audio's $379 nano iGalvanic3.0, which I find does its prescribed job of quieting, and unfuzzing, music streamed from my computer. The sonic effect of this noise reduction was that recordings sounded sharper, cleaner, and more three-dimensional—but not always more enjoyable, so I've never felt inspired to keep any galvanic isolator in my system. My brain rationalizes: if this add-on isolation is really so necessary, why is it not included with every DAC?

Connor sent me the $329 made-in-Germany Intona Technology 7055-C USB 3.0 SuperSpeed Isolator, which he said should provide better sound with the May DAC, especially when I use my laptop as source. Of course, I wanted to experience that.

According to Daniel Stämmler, Intona's CEO and chief engineer, "The intended purpose is complete isolation of both data and power lines. [The] resulting sound quality improvement is the effect of breaking all the noise coming from the host computer."As best I can tell, the Intona isolator breaks ground loops, minimizes coupling between data lines, and protects USB ports from power surges and voltage spikes. Sounds helpful and harmless, no?

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Footnote: 1 HoloAudio and Kitsune HiFi, 19410 Highway 99, Suite A #366, Lynnwood, WA 98036. Web: kitsunehifi.com