For his review of the Pink Faun 2.16x music server in the December 2020 issue, Kal Rubinson needed to use a Linux-compatible multichannel D/A processor. A little Googling uncovered the 8-channel dac8 PRO from Okto Research in the Czech Republic, so Kal borrowed one from the manufacturer. He found it to be a great-sounding DAC with an intriguing feature set. He purchased the sample.
For a couple of years, I have been following Prague-based Okto Research. At first, Pavel Krasensky, the founder and hardware developer, offered audio design ideas and DIY modules that I found tantalizing. For example, there was a dandy-looking ESS 9038Pro Sabrebased output module and some appealing power supply modulesbut to use those, the buyer had to manage inputs and integration on their own.
Then, finally, last year, Krasensky released the dac8 PRO, an 8-channel D/A processor with USB input and output, 8 channels of AES/EBU input, and 8 channels of balanced (XLR) analog output as well as a headphone output.
Three products are the subjects of lengthy followup reviews in the December issue of Stereophile: MBL's Noble Line N31 CD player-D/A processor, the GoldenEar BRX loudspeaker, and Alta Audio's Alyssa loudspeaker.
When Stereophile publishes followup reviews of various kinds in the print magazine, we add the followup as a "child page" to the full review. That means that they don't appear on the website's home page and might get missed. The October 2020 issue included three followups: of the Boulder 2108 phono preamplifier, the Weiss DAC502 D/A processor, and the IsoAcoustics Gaia loudspeaker isolation feet.
The email from Herb Reichert was intriguing. "I am, with great difficulty writing about HoloAudio's new two-chassis May DAC," he wrote. "It is death quiet and very natural. It makes every recording sound non-digital."
Once Herb had finished writing his review of the HoloAudio for the August issue's Gramophone Dreams column, I sped to his Bed-Stuy bothy and grabbed the May DAC, both to get it on my test bench and to take a listen for myself.
I am fascinated by DACs and the shifting sands of today's digital-audio marketplace. This month, I am reporting on two more DACs, both made by Denafrips: the $4498 Terminator, until recently their flagship DAC, and the $768 Ares II, the company's least expensive model. Like the HoloAudio May DAC I described last month, both Denafrips converters employ R-2R conversion schemes, and both render recordings into direct, unprocessed sound.
I felt like I'd just been offered a choice of 31 flavors of Baskin-Robbins ice cream topped with up to 57 varieties of Heinz ketchup, 57 condiments, and 47 brands of coddled cream. My head began to spin, my stomach churned, and my mouth grew very dry as I read that Gold Note's DS-10 ($2995) was a "chameleon DAC" with 192 setup options that enable it to "completely blend in with different music genres, giving the listener the opportunity to adapt the behavior of the unit to the music playing, to one's stereo system and, most of all, to the listener's taste."
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.
Hi-fi system resolution has long been the cause of heated arguments. But when it comes to converting digital data to an analog signal, there can be no argument. Data go in at one end of a DAC and an analog signal comes out of the other end, with a noise floor directly rated to the combination of the converter's digital and analog resolution. Ever since I started measuring digital products for Stereophile, I have been expressing a D/A processor's effective resolution in terms of the equivalent number of bits.
At the 2019 AXPONA, I took part in one of my first official meetings, as editor of Stereophile, with members of the manufacturing community: the German company T+A. They were presenting in the room of Texas dealer Lone Star Audio, which was owned by the late Jim Hench. They had a corner hallway to themselves: two rooms and, at the time when I arrived, a hallway table brimming with coffee and pastries. Fortuitous timing.
This unique device is a solution to a problem that previously couldn't be solved.
There are, of course, any number of little boxes that can extract audio from the HDMI video bitstream; they began to appear on the market to fill a need for a way to route audio from a player's HDMI output In the recent past, you could buy a good-qualityeven audiophile-gradeuniversal player and listen to SACDs via its good-sounding analog outputs. But good-sounding universal players are becoming scarce.
The idea of using digital signal processing (DSP) to convert digital audio data sampled at 44.1kHz or 48kHz to a higher sample rate is not new. I first heard the beneficial effects of upsampling at Stereophile's 1998 hi-fi show in Los Angeles, where a pro-audio dCS 972 digital-to-digital processor was being used to convert 16-bit/44.1kHz CD data to a 24/192 datastream.
In an era when polar opposites compete as absolutes, it can be a challenge to acknowledge the different and equally valid ways in which audiophiles approach musical truth. But the reality is that our perceptions of how reproduced music should sound are determined, to a large extent, by how we approach the live experience.
Even as digital/analog processors were becoming a hot product category in the early 1990s, audiophiles were also learning that timing uncertainties in the AES/EBU and S/PDIF serial datastreamsjitterwould compromise any improvement in sound quality offered by these DACs. Some companies therefore introduced products to reduce or eliminate jitterin the November 1994 issue of Stereophile, Robert Harley reviewed three such products: the Audio Alchemy DTI Pro, the Digital Domain VSP, and the Sonic Frontiers UltrajitterBug. I still have Stereophile's review samples of the UltraJitterBug and VSP, along with two contemporary DACs: a PS Audio UltraLink and a Parts Connection Assemblage DAC-1.
As our reviews of these products were published before Paul Miller's and the late Julian Dunn's development of the "J-Test" diagnostic signal, I performed J-Test jitter measurements to bring that 1994 review into the 21st Century. You can see what I found here.