DSD vs PCM with Resonessence Labs Herus DAC & Steely Dan


FOMO. Fear of missing out. I’ve been using the Resonessence Labs Herus in various system configurations for a good few months and not once have I been troubled by FOMO. Fear of missing out on a better sound from bigger, badder, more expensive DACs — e.g. Resonessence Labs’ own INVICTA Mirus, the AURALiC Vega, Metrum Hex or Aqua La Scala MKII. It’s THAT good.


The Herus is one of the many USB-powered DAC/headphone amplifiers to come to market in the past two years. It joins the Audioquest Dragonfly 1.2 (US$99), the HRT microStreamer (US$189, review here), Audioengine D3 (US$189) and the ALO ‘The Island’ (US$299, review to come) as a portable solution that fits in the palm of your hand. Like the ALO unit, the Herus feels solid in the hand, readily connoting a sensation of substance, and unlike the HRT unit, it doesn’t feel like you could damage the Herus easily. You could probably throw it across the room and it’d come off unscathed.


What sets the Herus apart from (most of) the competition for me are three features: 1) DSD support, 2) a Type B USB input socket and 3) a 1/4″ headphone output socket.

The Type B USB socket I’ve been able to stir audiophile USB cables from Light Harmonic and Total DAC into the mix; both of which really open up the Herus’ sound. Ironically, the filter on the Total DAC D1 USB cable is larger and heavier than the Herus itself!


The 1/4″ headphone socket means Mr Speakers Mad Dogs get a look-in without having to first don the awkward pants of a 1/4″-1/8″ adaptor (which is needed for the ALO, HRT and Audioquest units).

At US$350, the Herus is one of the cheapest entry points into the micro-world of DSD music. I’m still playing (the pragmatic) wait ‘n see game with DSD, not necessarily because I’ve yet to be convinced of its sonic benefits but because thus far VERY few mainstream-ish titles have seen the light of day. There are even fewer that fall into personal categories of ‘know’ and ‘like’. Thankfully, Steely Dan’s Gaucho is one such album. I suspect most long-term ‘Dan fans would (ahem) peg Aja as their finest work…but not I. For me it’s Gaucho all the way, a near-perfect, California-drenched mid-life crisis record.


Gaucho is now available from the Acoustic Sounds online store as a DSD download for US$25. US$18 gets you the 24/96 PCM download from HDTracks. The big question then: how do they compare sonically?

Illegal fun, under the sun. What follows is far from conclusive. It’s a sample of precisely ONE album across TWO systems. And after this piece is done, I don’t want to hear Gaucho for a very, very long time. I’ve been flogging the both downloads in my current portable headphone and two-channel setups all week. The Resonessence Labs Herus provided D/A conversion in both, proving just what a flexible little fella it is.


System 1 (headphones): V-Moda Crossfade M-100 w/ Memory Cushions, Resonessence Labs Herus DAC, Total DAC USB cable filter, Macbook Air w/ Audirvana+

System 2 (two-channel): Evolution Acoustics MicroOne, REDGUM RGi60 integrated, Resonessence Labs Herus DAC, Light Harmonic Lightspeed USB cable, Antipodes DS music server (review coming soon).


In both rigs, the results tumbled down the same.

Hollywood – I know your middle name. DSD serves up more texture – particularly on bass notes – but its presentation is softer, more easeful. The 24/96 PCM version pours in more caffeination, keener leading edge energy. It’s more forward sounding and perhaps a shade wider with soundstaging (which caught me by surprise). However, I can see how record lovers and NOS DAC diggers might prefer the DSD take; its closer to the qualities often (erroneously?) attributed to vinyl playback and filterless DAC solutions. If your system is chillin’ more than illin’, the HDTracks download is your guy. The DSD spin instantly recalls my recent foray into Blu-ray audio over HDMI: DSD sounds squishier; seeming more elastic.


When switching out the V-Moda cans for Mr Speakers’ Mad Dog headphones, I preferred the extra energy of the 24/96 PCM. It better cuts through the warmer, ‘vintage speakers’ vibe of the entry level Mad Dogs. Evolution Acoustics MicroOne are more ruthless with source material – here I’d peg the DSD as a better fitting suit.

So – what gives? I’d like to say I could pick a favourite but I just can’t. This standoff puts me me firm on the fence. DSD for more lively, thinner sounding systems, PCM for thicker, less energetic rigs. Cop out? Hardly. Different doesn’t always translate to better.


Yes, the Schiit Loki (US$149) is a cheaper DSD gateway but it doesn’t do PCM. Resonessence Labs mighty little Herus means you can try both for yourself in pretty much any system setup – no external power supply required. Don’t let its appearance fool you: it’s as suitable for portable audio solutions as it is for more luxurious two-channel configs. And it’s FOMO free. Good game Resonessence Labs, good game.

Further information: Resonessence Labs | Addicted To Audio | Acoustic Sounds | HDTracks

[The Resonessence Labs Herus will also work with an iOS 7-equipped iPhone or iPod Touch.]

Written by John H. Darko

John lives in the NOW + HERE = NOWHERE. He derives an income from the ad revenues of DAR. John is also an occasional staff writer for Stereophile, 6moons and TONEAudio.

Twitter: DarkoAudio
Instagram: DarkoAudio
Facebook: DAR


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  1. That’s why The Dan is such a timeless listen – both albums are great, just produced at different times in their career. Still one of the best jazzbluesrock bands to date…

    • Quite; even back in the day before I understood ANYTHING about the recording process, ‘Gaucho’ always struck me as sounding so ‘bright’ and ‘sparkly’ and clean.
      Then I started reading about SD considering themselves a studio band first and foremost and it all started making sense.
      Look, I still get the tingles listening to ‘Third World Man’ straight off my iPod or iPhone 5 through Shures or Ety’s; I HATE to think how much better it could sound…

  2. Hi John,

    I agree with your review. I wrote some of my initial impressions as a comment on your original announcement of the Herus:


    At the time I was using a simple USB A-to-B converter presuming no cable would be better than any cable. However, I recently purchased an AudioQuest Forest USB Cable for use with another DAC that is on its way, and tried it out with the Herus in the mean time and I have to say it is a significant improvement. My initial impressions with the A-to-B converter were a bit nonplussed, but with the AudioQuest cable I’m preferring the Herus over the other options I have.

    I’ve also tried the Herus with my amplifier and would be interested to see how much better it would sound with RCA outputs and independent power supply. I agree with you that it is great value for money in terms of sound quality and features.

  3. I will definitely have to pick up one of these babies soon. The fact it works natively with my older Samsung S3 phone without the need for USB Audio Recorder Pro is another plus in my book! As for my iPad, a CCK kit + Onkyo HF Player app & I’m good to go on the front too. For those without the need for cans, I’m suspecting the half as expensive ifi nano iDSD maybe the better deal but that’s just speculation & personal bias on my part as I favor Burr-Brown>ESS.

  4. realhd-audio.com John Siau: Benchmark Audio Guru by Mark Waldrep

    “I actually had a SONY engineer say to me one time and this is quite few years ago…he said, ‘we realized after we got a ways down the road that DSD was kind of a mistake but we had too much invested in it’. ”

    First comment is of John Siau:

    Where does Benchmark stand on DSD vs. PCM, and why?

    1. Benchmark recognizes that DSD (64x and higher) has significant advantages over 44.1/16 PCM.

    2. Benchmark recognizes that high-resolution PCM (96/24 and higher) has significant advantages over 44.1/16 PCM.

    3. Benchmark’s measurements and calculations show that the performance of 64x DSD is almost identical to the performance of 20-bit 96 kHz PCM (the in-band SNR of 64x DSD is about 120 dB). 64x DSD does not have any time-domain, frequency domain, or linearity advantage over 96 kHz PCM. DSD marketing materials have been very misleading.

    4. 24-bit 96 kHz PCM has a 24 dB noise advantage over 64x DSD (144 dB vs. 120 dB), but this 24 dB noise difference is completely masked by the noise produced by other components in our recording and playback systems, and by the noise limitations of our recording and listening spaces.

    5. Benchmark recognizes that 64x DSD and 96/24 PCM formats outperform most of the recording and playback chain. Bandwidth of either digital transmission system meets or exceeds the bandwidth of our microphones, amplifiers, and speakers. Likewise, the SNR of either digital transmission system meets or exceeds the noise performance of microphones, microphone preamplifiers, and power amplifiers. In addition, these digital transmission systems both exceed the performance of most A/D and D/A converters. 64x DSD and 96/24 PCM are not the factors limiting the performance of our audio systems. Focusing on DSD vs. PCM will distract us from much bigger issues in the recording and playback chain. Any sonic advantage of one digital system over the other will be very small when compared to improvements that can be made in other parts of the signal chain.

    6. 64x DSD and 96/24 PCM both offer excellent sonic performance as distribution formats. PCM is more compact, but DSD provides better copy protection (a frustration to those of us who use music servers, but an important consideration for copyright holders).

    7. Every A/D and D/A converter that Benchmark has produced uses Sigma-Delta conversion with equally-weighted 1-bit conversion elements. Benchmark never used multi-level conversion because of the THD issues caused by the linearity errors that are common to all multi-level systems. Benchmark has always placed high priorities on THD and linearity, at the expense of SNR. Sigma-delta 1-bit DACs tend to produce more noise than multi-level systems (such as ladder DACs), but the 1-bit systems achieve near-perfect linearity, which in our opinion is much more important than SNR. Benchmark has overcome the noise limitations of 1-bit conversion through the use of parallel 1-bit conversion systems. Our DAC2 sums the outputs of four balanced converters. Each of these four converters has sixteen equally-weighted balanced 1-bit converters (for a total of 64) that are summed together to improve the SNR of the system. These 64 1-bit converters can be driven from a 32-bit PCM signal, or from a 1-bit DSD signal. Either way, the performance is nearly identical, and none of the multi-bit THD issues exist. In this sigma-delta configuration there is almost no difference between the in-band performance of PCM vs. DSD. The only measurable difference at the output of the DAC2 is that 64x DSD signals produce about 8 dB more noise in-band than 96/24 PCM (due to the SNR limitations of DSD). Ultrasonic noise is not an issue at the output of the DAC2 because we are careful to remove the ultrasonic noise produced by DSD noise shaping. These same filters also remove the ultrasonic images that are always produced by D/A conversion (DSD or PCM).

    8. The ultrasonic noise produced by DSD noise shaping must be removed after D/A conversion. It cannot be removed from the DSD signal before D/A conversion. This noise is due to the 6-dB SNR of the 1-bit DSD transmission system. Aggressive noise-shaping must be used in the DSD A/D, and at least once more in the mastering process. This noise-shaping is used to achieve an excellent SNR in the audible band by moving most of the 1-bit quantization noise to ultrasonic frequencies. Each time this process is applied, the quality of the DSD audio degrades (noise and distortion both increase). For this reason, the quality of DSD degrades very quickly in the mixing and mastering process. DSD has produced impressive results when the mixing and mastering processes have been omitted from the signal chain. To date, most of the DSD vs. PCM listening tests have omitted these processing steps. Unfortunately very few recordings can be produced without some mixing, editing, and mastering. Cascaded DSD noise-shaping processes should be avoided. For this reason, Benchmark does not recommend recording and mixing in DSD.

    9. The 24-dB noise advantage that 24/96 PCM has over 64x DSD begins to become significant in the mixing and mastering processes. In terms of in-band noise, each DSD noise-shaping process is equivalent to at least 16 cascaded 24-bit dither processes. In terms of distortion, there is no comparison; the DSD noise-shaping process adds distortion while the PCM dithering process is distortion-free.

    10. If the ultrasonic noise of DSD is not removed after D/A conversion, it will usually cause distortion in the playback system. The slew-rate limitations of most power amplifiers will fold the ultrasonic noise into the audible band causing distortion that is not harmonically related to the music. If the power amplifier has sufficient slew rates to pass the ultrasonic frequencies, similar problems will occur in the speakers. For these reasons, the ultrasonic noise must be removed from a DSD source after D/A conversion or before amplification.

    11. Benchmark introduced 64X DSD on the new Benchmark DAC2 converter family. This gives our customers the ability to play DSD recordings in native format. Existing DSD recordings should not need to be converted to PCM to be enjoyed on a Benchmark converter.

    12. Currently there is no practical way to play SACD disks through a high-quality outboard converter. SACD copy protection holds most existing DSD recordings captive to the limited quality of the low-cost conversion systems built into SACD players. It is our hope that many of the fine recordings that exist on SACD disks will be released for purchase as DSD downloads.

    • Thanks @maty – I’m happy to leave the theoretical debate to those who are far more technically-minded than I. Instead, my questions re. DSD are more fundamental: 1) What’s available? and 2) How does it sound?

  5. But the Loki was made with a different purpose .. As an add on to an existing PCM DAC.
    And I believe iFi audio has at least two DSD/PCM option in this Herus price range if not cheaper

  6. Yep, I also remain in the “maybe DSD later” camp. Though I have FOMO (great acronym) too, the transparency, texture & timbre, and dynamics provided by “lowly” flac 16/44 rips (thousands of choices) via Jplay/bel canto mlink/Bifrost Uber chain are STILL jawdropping. So being patient is easier than ever.

  7. Hi John,
    I have the Mirus DAC in my main system so I am familiar with the Resonnesence brand. I heard their other units at RMAF last October as well. I would highly recommend listening to lower rez (anything below DSD) stuff upsampled to 2xDSD. IMO that would probably do away with most of your doubts about whether the DSD capability was worth it. This is coming from a former NOS DAC guy. If you are using the latest JRiver player you can easily set up 2 Zones, one for straight DSD and one for the upsampling mode for (relatively) quick comparisons.
    All the best and thanks for the informative website.

  8. Now that you have an acceptable DSD download, can you comment on the sound of the Schiit Loki vs Herus for DSD-only?

  9. I’d like to read about more comparisons between PCM and DSD which involves actually listening to the original master tapes too and opinion of what sounds closest to the original source. Not just most euphonically colored.

    • You probably won’t see that kind of coverage in these pages. You won’t even see this kind of ‘DSD vs PCM’ piece too often; whilst there remains so very little DSD music out there I’d rather dedicate my time to DACs that make Redbook (plus a little hi-res) sound good with the thousand upon thousands of songs I (and other readers) already own.

  10. I’m hesitant to wade into the DSD vs PCM comparison. I’ve only got limited experience: a Sony SACD player and the Herus DAC.

    I’ll use this DSD128 and 24/192 binaural track as an example:


    With the DSD version I had a real sense of 3D placement with the music coming from slightly below and to the front and left. If you have a look at the video this seems close to how they recorded it. With the 24/192 version I don’t get that sense.

    My guess is that DSD has the time precision to represent fairly accurate 3D placement. In contrast the 24/192 version sounds like a bunch of music coming through the headphones.

    Having said that, I actually enjoy the 24/192 version more since it sounds more melodic. DSD seems to be missing something.

    I’m going to guess that DSD is missing amplitude precision in the higher frequencies.

    Theoretically amplitude precision should be improved on DSD with higher sampling rates, and time precision on PCM should be improved with higher sampling rates. So my prediction is that we will see both DSD512 and 24/768 becoming available in the future. I’ll also predict that PCM will win as it is simpler to mix, etc., and can be played through an R2R DAC.

    Note: most of my conclusions come from listening to a $350 USB powered headphone DAC! It is also possible that some of the differences I am hearing are specific to the ESS Sabre DAC.

    • Yes, I hear time domain accuracy is one of DSD’s strengths. Thanks for posting your listening ‘test’ thoughts – appreciated. 🙂

  11. What you describe as the difference between DSD and PCM is what I’ve heard for some years in my own comparisons. I had a Meridian system for a longtime, and would compare DVD-A to SACD (through a somewhat different pathway). Lately I compare via streaming, though as you point out, this is relatively little to do so with

    My general findings: the SACD was almost invariably softer/smoother sounding, but gave up transient edges and some dynamic energy. It’s a more ‘audiophile/analog-like’ sound, but not necessarily more true to the source (Neil Young’s guitar should sound pretty damn rough) nor one I necessarily enjoy more. My own take is that a lot can get lost in the pursuit of smoothness — in music, tequila and many other things — and I think it’s barking up the wrong tree to choose a source/format based on your system voicing, but that’s another story. Basic point here is that DSD has the buzz now (if not the library), but is by no means a home run as the better format over high rez PCM.

    Coupla things worth checking out, Bob Stuart’s (of Meridian, a PCM proponent and inventors of MLP used by bluray, so take as you will) takes on DSD vs. PCM, and the Ayre site, which has some comparison tracks on both formats and an essay of how they feel about it. Bottom line is they’ve added DSD to the QB-9 DAC not because they think it’s better, but to meet the market.


    • DSD is very much buzz over library right now. Many manufacturers that I’ve spoken to are only adding DSD to meet market demand…which brings us back to buzz.

  12. This is the hottest of audiophile topics these days. EVERYONE, who is a self professed ‘audiofool’ wants to do some DSD, the way its ‘supposed’ to be done. I’m one of those. Its great, new capabilities with unrealized potential etc. I have some news hot off the press… Got the iDSD – does DSD sound great? Hell ya! Here’s the other take away from this new silicone. It does EVERYTHING better. Dont get locked into lusting for DSD when you have 5,000 CD’s ripped to hard drive. Its silly. Lets focus on what makes WHAT WE HAVE sound great!

  13. hi john,
    I did appriciate the review as almot always. I’m currently using a HRT microstreamer and am now wonderin if the higher audio quality would be that significant. But I trust your words and thinkin about sell the HRT for the resonnace labs herus. I was wondering if ther will be a 3rd part on your herus review as it is not yet classified in your DARKO dac index. Lookin forward to read you. Best regards. Dookie182

    • I’ll be adding it to the Darko DAC Index once it’s been re-vamped. Workload wise, I’m a bit swamped at the moment. Main priority this week and next is the Antipodes DS Reference server review for 6Moons.

  14. I’m wondering why my previous reply just disappeared. Anyways. Are you preparing a last part review on the Herus? I didn’t see it added in your darko dac index yet. I have the HRT microstreamer on hand and still looking for better, so the fact that you havent’ been bothere with fomo even knowing classier big guys dac is a bold saying… that might even be true comming from you. wondering how it compares to it’s family class concerto devise.
    best regards.

  15. Great review John! As a small-scale High End Audio manufacturer and Electrical Engineer, I would like to make a few comments. For a while now I have (happily) used an extensively modified ESI Juli@ sound card for my computer audio with Windows 7 64 bit and JRIVER. My ATX format tower is fast, has a better-than-stock power supply (it pays to do your research here) and uses Sun Audio Labs Computer Power Supply Filters (which remove switching noise and smooth current delivery). It has been a pretty tough customer; making many DACS walk away with their proverbial tails between their legs.

    When High Resolution downloads became available (the 24 bit PCM’s) I was elated. FINALLY we have a digital format for the home that can deliver and do so reasonably. Then DSD came on the scene and I thought ” Oh great! Format war! Why couldn’t the industry leave well-enough alone?”. I suspect at least part of this is Sony is trying to recoup their SACD losses….or at least some of them; however, DSD is valid if used correctly and that remains to be seen.

    The various recording studios have master tapes which are in analog, PCM and DSD. The various studios out there still record in all three! Regarding consumer hi-rez downloads, if they sell DSD for the analog and DSD master tapes and sell PCM for the PCM master tapes; we all win. If they are taking 24 bit PCM master tapes and converting them to DSD just for the sake of making a DSD, it does not make sense at all. It is all in how they use these formats which will determine ultimate sound quality and I believe market success. As of right now, it appears to me that DSD is being “abused” because I know of DSD releases where the original master tape was PCM. The thing to keep in mind is this: If you do wade into DSD waters and DSD downloads go “belly up”, you can always convert them to a 24 bit 176.4Khz FLAC or WAV and still have a very nice sounding recording if you use the right software. I have experimented with such conversions on JRIVER and they sound wonderful.

    I have experimented with many DACs and not too long ago I purchased a Herus out of morbid curiosity (it was the DSD thing). The DSDs I have downloaded (I have been selective regarding WHAT the original master tape format was) do sound very nice. The Herus also does PCM very well. Overall, this $350 USD DAC is one of the best sounding DACs I have had in my system; even surpassing my extensively modified and shielded Juli@! It sounds really good right out of the box, but LOTS of run-in time is of great benefit. When you are not listening, keep something playing anyway. Just turn the volume clear down, hit “mute”, change your “selector switch” etc…. Another thing; this DAC is deserving of a USB cable that probably costs as much as the DAC. It will sound good with lesser cables, but buying better cables for this DAC will not be money wasted.

    I am a 30 year audiophile, an Electrical Engineer and I work in this business. I do not recall the last time I heard so much for so little. When used properly, the Herus is a Giant Slayer.

  16. I suspect with the Herus you do not fear missing out the Mytek Stereo192 DSD DAC and on the other hand would still listen with total satisfaction to that Mytek if we took the Herus and all other DACs away. Which one would you prefer when?

    BTW, thanks for updating the DARKO DAC index!

    • I’ve yet to compare the Mytek and the Herus directly. I shall soon though.

      The Index will see a more radical overhaul this weekend.

  17. So, is it possible that the Herus [from computer to amp via 1/4″/RCA adapter cable] is sonically equal to Concero HD [from computer to amp via coaxial], not counting the DSD128 mode S/PDIF limitation, or even equal to Concero HD [from computer to amp via RCA] at a savings of $500?