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-5xeMP 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.

COMPANY INFO
HoloAudio
US distributor: KitsunéHiFi
19410 Highway 99, Suite A #366
Lynnwood, WA 98036
ARTICLE CONTENTS

COMMENTS
Bogolu Haranath's picture

All the people who own sizable CD collection could try R-2R DACs like May DAC and/or Denafrips DACs, and use their NOS filters :-) .....

Bogolu Haranath's picture

JA1 did a comparison between May DAC and Weiss DAC502 ...... JM has MBL N31 player/DAC ...... May be JM could do a follow-up comparison review between May DAC and MBL N31 :-) .......

davemill's picture

+ Bricasti Design M21. I am looking for a ladder DAC with volume control. :-)

Bogolu Haranath's picture

Bricasti M21 costs $19,000 ...... If you don't mind a pre-amp, you could use a pre-amp like the Parasound JC 2BP which has gain controls (reviewed by Stereophile) ...... May DAC + JC 2BP cost less $10k :-) .......

davemill's picture

Thanks Bogolu! For some reason, I thought the M21 was $13K. I am trying to stay away from another component. To be consistent with my current system, it would mean another $3250 for another XLR and power cable. Something to consider though as the M21 is expensive. :-)

Bogolu Haranath's picture

You are welcome ...... You could donate that extra $10k to me, since I'm thinking about buying the May DAC + JC 2BP, myself :-) .......

davemill's picture

Congratulations! Someone on the audioaficionado site mentioned that the M21 is $8K more than the M3 which is $5K. I need to follow up on the price. If you are correct, I may make the same choices as you. I currently have a A21+ amplifier so that pre-amp would look at home. Why are you going for it versus the LA-4?

Bogolu Haranath's picture

I checked the price of M21 DAC on the internet ...... LA4 would be a good choice too ...... JC 2BP has HT bypass (a.k.a processor loop) ........

Bogolu Haranath's picture

If you listen to headphones also, HPA4 would also be another good choice :-) .....

Glotz's picture

And as you remember, I purchased it and LOOOOOVE it. Just food for thought.. lol.

JRT's picture

Bogulu, If you want the reference grade Benchmark HPA4 ($3.3k) preamplifier / headphone amplifier, why not also get the reference grade (non-R-2R) Benchmark DAC3 B ($1.8k), and maybe add a (non-Benchmark) WiiM Mini ($0.08k) streamer, and a pair of (also non-Benchmark) Buckeye Purifi 1ET7040SA Monoblock v2 amplifiers ($0.95k per each).

barrows's picture

We (Sonore) used the M21 for our demo system at RMAF in 2019. Sonore Signature Rendu SEoptical renderer-M21 DAC-M25 power amp-Vivid Audio Kaya 45 speakers.
The system sounded fantastic both via the R2R section of the M21 for PCM, and especially via the discrete, single bit converter section for DSD.
I would offer a very high recommendation for the M21. The price is actually very, very fair, as the the build quality (inside and out) on the Bricasti DACs needs to be seen to be appreciated. Also consider that the M21 features three separate DACs internally: dual chip SD DAC for DSD and PCM, dual chip R2R DAC for PCM, and a discrete single bit converter for DSD, and made in uSA of course, with outstanding customer service from Bricasti.
After hearing what the M21 could do for DSD input, I purchased its little brother the M3, which has the same discrete single bit converter stage for DSD, and analog volume control as the M21. I convert all formats to DSD 256 in the server, and send that to the M3 for final conversion, and this approach sounds fantastically good here, direct to amp, using the M3's analog volume control.

georgehifi's picture

They are really missing out on % of sales with some that prefer to go direct to power amp and control the volume from the dac.
Love the test report, especially how clean the -90db wave forms are, and low impedance drive capabilities down to 600ohms!! which at 3v-se, 6v-bal out deserves a volume control.

Cheers George

BillBrown's picture

I would love to listen to this DAC both in NOS mode and in NOS mode with upsampling and a filter in SW in my computer- I use Audirvana with an iZotope filter similar to Ayre's "Listen." I would then use Audirvana's volume control in my preamp-less system.

Bill

Herb Reichert's picture

remind all you preamp-less folks that gain management is one of the most important considerations a recording studio or home audiophile must address. Overall system gain affects signal-to-noise levels, perceived dynamics, and the ability to make subtle (but not too subtle) volume level adjustments.

hr

Bogolu Haranath's picture

Both Benchmark LA4 and HPA4 have 256-step volume controls ...... So, gain controls may not be a big issue :-) ......

Kal Rubinson's picture

Yes, the Benchmarks are excellent but how one manages system gain best depends on all the components in the chain, not just on the presence/absence of the preamp.

Kal (preamp-less)

Herb Reichert's picture

I am talking about an audio system's total gain-matrix which is the gain sum of all active stages. Typically an amplifier has 22-27dB and a line-level preamp has 5-10dB. Most well-managed audiophile systems come in around 30-35dB total. 20dB total is very low. 40dB will scare your pets and make the volume control almost useless.

h

Bogolu Haranath's picture

If you (KR) are using the Parasound A31 and A21+ for your 5-channel surround sound system, they come with built-in gain controls ....... That should help .....

I thought you are/were using the Okto dac8 Pro, 8-channel DAC/preamp with volume control for your surround sound system? .......

Both LA4 and HPA4 are 2-channel preamps ...... You have to use 3 of those preamps for your 5-channel surround sound system :-) ........

Kal Rubinson's picture
Quote:

If you (KR) are using the Parasound A31 and A21+ for your 5-channel surround sound system, they come with built-in gain controls ....... That should help .....

Nope. I have neither of those amps. However, the Benchmark AHB2 are more suitable with its gain selections.

Quote:

I thought you are/were using the Okto dac8 Pro, 8-channel DAC/preamp with volume control for your surround sound system? .......

Yes but I have other DACs and sources.

Quote:

Both LA4 and HPA4 are 2-channel preamps ...... You have to use 3 of those preamps for your 5-channel surround sound system :-) ........

I've already done that but it is clunky and inconvenient.
https://www.stereophile.com/content/benchmark-la4-line-preamplifier-multichannel-application

Glotz's picture

the combo of the LA4 and the AHB2 have almost no equal at the price. 3 settings on the amp and 10db worth of volume level changes on the pre- and the quality of the sound doesn't change one iota at any gain or volume setting choice. Level matching sources is a breeze.

BillBrown's picture

I definitely agree, Mr. Reichert. It is often overlooked, but very important. Optimally any attenuation should be minimized, digital (especially) or analog. Ideally everything should be running close to "wide open" at optimal listening levels.

The analog preamp is interesting these days with many DACs having volume control, analog and/or digital. Both the analog output stage and the digital attenuation scheme in these DACs must be excellent.

There was an era where passive preamps rose to prominence (the 90s?). This brings important considerations in impedance. I used a set of EVS "ultimate attenuators" in that era (two small boxes plugged directly into the amp RCAs with a rotary switch selecting individual resistors). Thankfully it was a headphone system so I was sitting next to them. :)

Later I built a transformer-coupled DAC (GREAT sound) that needed minimal attenuation.

Many reviewers found passive "preamps" lacking, especially in dynamics. JA has always emphasized the importance of active line stages, describing them as the most important link. Many preferred a great active line stage to passive, and several since have noted improvement bypassing DAC volume controls and using external line stages.

Back to gainstaging. I sold off my entire system before going overseas in 2012. I was full-on exotica to that point (tubes, vinyl, stats, etc.). When I returned and build back up I did it slowly and less exotically, leaning toward pro stuff and simplicity. I use an RME ADI-2 at its lowest gain setting into a Benchmark amp at its lowest setting and listening with a total of 0.5 to 6db of attenuation (with the volume control in the RME) when listening. It is pretty cool.

If I could get the gainstaging right, I wouldn't hesitate to use the Holo DAC with a bit of digital attenuation.

Best,

Bill

Bogolu Haranath's picture

I can see an ad ....... Want cure for audiophile depression? .... buy D'Agostino Momentum HD preamp ($40k, reviewed by Stereophile :-) .......

Jason Victor Serinus's picture

Of course, not everyone reading my rave review of this monster preamp will have the spare cash to buy one in the middle of a pandemic. But high-priced gear is reportedly selling well of late. I still consider this baby a "monster" that intensifies colors in a distinctly musical way, increases size and weight of images, and raises a system a major level.

Way back, I tried a friend's passive preamp. I found that it detracted rather than added to the presentation. Not so with many of the active preamps that have come my way for review.

jason

MhtLion's picture

Based on my readings elsewhere, I believe the best way to achieve May's peak performance is to use external DSD conversion/oversampling - like HQPlayer to convert any PCM to DSD 512 - then to feed May in NOS mode.

barrows's picture

I wish reviewers would test equipment like the May this way, with HQPlayer (or even just via Roon, which still does pretty well oversampling to DSD 256). The oversampling chip used in the May has been shown in measurements to be pretty poor in performance when compared to HQPlayer, which is not surprising consider the difference in processing power available in a small chip like that, compared to what HQPlayer uses in a computer server to oversample to DSD 256...
Continuing in this vein: again I find lacking that when Stereophile measures DACs which have completely separate conversion paths for DSD and PCM that they do not provide complete measurements for DSD and PCM. I would want to see complete measurement sets for DSD and PCM, and also including spot measurements for oversampling to higher rates in software.

georgehifi's picture

"Overall system gain affects signal-to-noise levels"

Yes and if you don't use all the source has to offer, your just adding more noise from the active preamp gain stage. (really think about it, your shunting the source signal to ground with a active preamp volume control just to make it back up again with it's own gain stage)
Most sources today can output well over 3v, most amps only need .5v to 1.5v in for full wattage output!!

Quote from Nelson Pass:
Nelson Pass,
“We’ve got lots of gain in our electronics. More gain than some of us need or want. At least 10 db more.
Think of it this way: If you are running your volume control down around 9 o’clock, you are actually throwing away signal level so that a subsequent gain stage can make it back up.
Routinely DIYers opt to make themselves a “passive preamp” - just an input selector and a volume control.
What could be better? Hardly any noise or distortion added by these simple passive parts. No feedback, no worrying about what type of capacitors – just musical perfection.
And yet there are guys out there who don’t care for the result. “It sucks the life out of the music”, is a commonly heard refrain (really - I’m being serious here!). Maybe they are reacting psychologically to the need to turn the volume control up compared to an active preamp.”

Cheers George

Bogolu Haranath's picture

You may be interested in reading the article 'Relay-controlled volume' on Benchmark media blog :-) .....

Kal Rubinson's picture

A volume control should, in almost all cases, really be called a signal attenuation control. It is very, very rarely a gain control and, generally, system gain is determined by a number of elements with fixed gain.

One consequence of this is that the more you attenuate the signal the more you reduce the SNR since the noise is fixed). So gain management consists of adjusting and/or selecting a chain of components that will amplify the signal enough to listen to and not much more.

Of course, that is constraining in use so having a variable attenuator somewhere is useful. Where to put it and how to construct it are separate matters.

Bogolu Haranath's picture

A preamp like the JC 2BP has both gain controls and volume control ...... Does that work? :-) ......

Recenty reviewed MBL N11 preamp has both unity gain control and volume control ...... Does that work? :-) .......

Kal Rubinson's picture

Without examining either of those, I will say that it is not about a single component. System gain matching involves all the components in a system. Some individual ones make the effort easier.

Bogolu Haranath's picture

You (KR) reviewed both the JC 2BP and the A21+ :-) ........

georgehifi's picture

Yeah, you can get them SE or Bal like this one.

https://www.ebay.com.au/itm/Finished-Relay-Volume-controller-Balanced-Po...

Cheers George

Bogolu Haranath's picture

Are they 256-step volume controls like the Benchmark LA4 and HPA4? :-) ......

georgehifi's picture

read the ad.
I have the SE one somewhere around here with remote and 4 inputs, very well built, same guy.
https://www.ebay.com.au/itm/Finished-HIFI-Remote-volume-Controller-128-s...

Cheers George

Bogolu Haranath's picture

Why are you not using it? ...... Is it still working? .... Are you sure it is the same Benchmark guy who built it? :-) .......

georgehifi's picture

There's even better, look at my avatar! the only thing that betters it, is source with digital domain volume control direct to amp. (so long as it's not use too low (<75% of full) as to introduce "bit stripping")

Cheers George

Bogolu Haranath's picture

The only thing that can better the Lightspeed Attenuator is a preamp which has 1024-step, relay-controlled volume ....... Just kidding :-) .....

Why not try the Parasound JC-5 or the A21+? ....... They both come with built-in gain controls :-) .......

Kal Rubinson's picture

Are they gain controls?

Bogolu Haranath's picture

See, my comments above :-) .....

Bogolu Haranath's picture

AHB2 has built-in gain control settings ...... Are they gain controls? :-) ......

Kal Rubinson's picture

Yes.

georgehifi's picture

@John Alexander, would be nice one day to measure, an R2R dac with digital domain volume control to see at what level those dacs start to "bit strip" Wadia and ML have been aware of it since the early days.
As this from Wadia states with final gain stage setting to get the max resolution from using a digital volume. https://ibb.co/vcd8dMP

Cheers George

georgehifi's picture

"Are they gain controls?"

Level/gain Kal, they both control the sources signal voltage going to the amp, one just does it cleaner and is direct coupled without any active components in the signal path, causing added coloration's and distortions, that aren't needed to begin with. As the sources today have all the voltage they need to drive amp to full output and much more these days. Just as Nelson Pass stated above.

Cheers George

Bogolu Haranath's picture

So, what does Nelson Pass do with his preamps ...... How does he design them? :-) .......

georgehifi's picture

Makes money, he's not stupid!

Cheers George

Bogolu Haranath's picture

'Do what I say, but don't do what I do' :-) ......

Bogolu Haranath's picture

You may also be interested in reading JVS' interview with Jugen Reis, designer of MBL N11 preamp ...... In that interview Reis describes his 'unity gain' design principles :-) ......

georgehifi's picture

Like I said, he supplies to the market that want them, and makes money from those preamps, he's not stupid

Cheers George

Bogolu Haranath's picture

'If you build them, they will come' ..... especially, if your name is Nelson Pass :-) .......

Bogolu Haranath's picture

JA2 could do a follow-up comparison review(s) between Pass Labs XP-22 ($9.5k) and Pasound JC 2BP ($4.5k)) and Benchmark LA4 ($2.6k) :-) .......

Jason Victor Serinus's picture

As far as I know, Nelson designs the amps, not the preamps.

georgehifi's picture

Interesting Victor, didn't know that, well if right that makes his quote about passive preamps quote look even more legit in what he says.

Nelson Pass:"What could be better? Hardly any noise or distortion added by these simple passive parts. No feedback, no worrying about what type of capacitors – just musical perfection.really - I’m being serious here!".

But there is a impedance matching proviso with 10k passive preamps as their highest output impedance is around 2.5k.
First "the amp" input impedance has to be more than >33kohm input impedance (most are except for some Class-D's), and "if" it has capacitor input coupling, the cap has to be 5uF or higher or bass roll off will occur.
Second "the source" should have a low output impedance, most solid state ones are. But many tubes ones are not.

Cheers George

Bogolu Haranath's picture

So, Pass preamps work well with Pass designed power-amps ....... just like, darTZeel preamp and power-amp combo :-) ........

That kind of a combo could provide a transparent window between the source and the loudspeakers (straight wire with gain) :-) ......

cdc's picture

I thought Stereophile had a 5 dealer minimum policy before reviewing a product.

But Holo has no USA dealers and you have to shell out $4,9898.00 sight unheard with NO refunds? Sounds pretty crazy to me.

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