Digital Processor Reviews

In 1978, when I reviewed Sony's first audiophile-type PCM-1 converter, I earned the undying scorn of a large segment of audiophilia by reporting that, on the basis of a rather short testing period (which did however include some live recording), I was unable to hear anything the matter with its sound. Four years later, but after substantially more testing, I am obliged to report the same thing about the PCM-l's son, the PCM-Fl.

With the furor over the launch of DAT (digital audio tape), it is worth remembering that commercial digital recorders have been with us for some time now: it is now nearly a decade since studio PCM converters were first successfully used for audio recording in conjunction with a VCR (which uses a helical spiral recording via a spinning drum to achieve the high writing speed).

When Stereophile publishes a followup review in the print magazine, we add it as a "child page" to the website reprint of the original coverage. We have recently done so with three significant products: the Magico M2 loudspeaker, the Linear Tube Audio Z10e tubed headphone amplifier/integrated amplifier, and the Okto Research dac8 PRO multichannel D/A processor.

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 Sabre–based output module and some appealing power supply modules—but 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.

Two of the followup reviews that were published in the November 2020 issue of Stereophile have been posted to the magazine's website: Herb Reichert on the Yamaha A-S3200 integrated amplifier and the measurements of the Denafrips Ares II and Terminator D/A processors.

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.