HoloAudio May (Level 3) D/A processor

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.

The review sample was the top-of-the-line Level 3 version ($4998), with both the processor and power supply having the serial number 1911541872. The May has four operating modes: NOS (for Non-OverSampling); OS (OverSampling PCM data to higher-frequency PCM and oversampling DSD data to higher-frequency DSD); OS/PCM (oversampling PCM and DSD data to higher-frequency PCM); and OS/DSD (oversampling PCM and DSD data to DSD).

Listening
The system used for a weekend’s worth of listening tests comprised either my KEF LS50s or the GoldenEar BRXes that I review elsewhere in this issue, driven by Parasound Halo JC 1+ monoblocks via AudioQuest K2 speaker cable. As the HoloAudio doesn’t have a volume control, I connected it and the Weiss DAC502 that I was going to compare it with to an NHT PVC balanced passive control unit with 2m lengths of Canare cable. Another 2m pair of Canare cables connected the PVC’s ¼” TRS output jacks to the Parasounds.

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The Weiss sounded a little darker, with slightly less soundstage depth, than it did when connected directly to the amplifiers, but it is important to keep everything the same for tests like this. Because the output of the Weiss is 1.4dB higher than that of the HoloAudio, I set the DAC502’s volume control to –1.5dB, ensuring that the levels were matched to within 0.1dB. The source for the comparisons was my Ayre C-5xe^MP playing CDs and sending data to each DAC via AES/EBU.

The first surprise was that the HoloAudio shows the CD’s track number and elapsed time on its display. I can’t remember ever seeing that before with a processor sent a serial datastream. The second surprise was how good the May sounded in NOS mode. Playing “The Mooche” from Stereophile‘s Editor’s Choice CD (STPH-016-2), Marty Erhlich’s alto saxophone and Art Baron’s trombone sounded natural, with superb palpability to their images. Jerome Harris’s acoustic bass guitar and Billy Drummond’s kickdrum had an excellent sense of drive, and his snare-drum rimshots lit up the acoustic of the recording venue, resulting in good image depth. Changing to the Weiss, which paradoxically sounded slightly louder than the HoloAudio despite being 0.1dB quieter, the balance got a little darker. The sax and trombone had a touch more midrange body, and the drums moved a little forward in the soundstage.

Playing the June issue’s Recording of the Month, Translations from the Portland State Chamber Choir conducted by Ethan Sperry (Naxos 8.574124), both the May in NOS mode and the Weiss offered superb soundstage depth with well-defined stereo imaging. However, the solo voices in the title track sounded more palpable with the May, and the fine detail of the sound of the bowed hand bells at the end of this track was clearer than it was with the Weiss. However, the solo cello in “In Paradisum” was a touch less full-bodied on the May than it was with the DAC502, and the low-bass entry at the start of “In Paradisum” was a tad better anchored than it had been with the May.

After several more comparisons between the Weiss and the NOS May, using recordings of many different kinds of music, I was confident that the differences between the two D/A processors were consistent, but they were always small. I could live with either. How about the HoloAudio’s oversampling DSD mode, which I understood HR had preferred to the OS and OS/PCM modes?

DSD vs NOS
Comparing DSD with NOS was more difficult than it had been with the Weiss, due to the DSD mode’s lower output level. Marking the PVC’s volume control where it had been for the earlier comparisons, I played the 1kHz, –20dBFS tone on Editor’s Choice and measured the voltage at the speaker terminals. I switched to OS/DSD and increased the volume until the amplifier’s output voltage was the same as it had been in NOS mode. I marked that control setting.

Instantaneous A/B comparisons were problematic in that the May took a long time to relock to the AES/EBU input when the mode was changed. Nevertheless, DSD sounded slightly quieter than NOS, even with levels matched. The cymbals in “The Mooche” were smoothed over in DSD, with slightly less top-octave air. Bass guitar on this track had more body with DSD, but there was better depth on the drums in NOS. Steve Nelson’s vibes were also projected a little more forward in NOS mode. However, the choral climaxes in the Portland State Chamber Choir CD clogged up a little in NOS while remaining clean in DSD.

The biggest difference between the two modes was with solo piano recordings. My recording of Liszt’s Liebestraum, performed on a Steinway D piano by Robert Silverman (from Sonata, Stereophile STPH008-2), sounded equally palpable in DSD and NOS modes. However, the NOS piano acquired a clangy quality at climaxes, while the DSD piano remained clean and closer to the sound of the instrument with the Weiss DAC502 decoding the digits.

Summing Up
The HoloAudio May (Level 3) is one of the best-sounding D/A processors I have tried. I suspect that if I had more than a weekend to live with it, I would end up changing modes for each piece of music I wanted to play.

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