Is a pre-amplifier still relevant to digital audiophiles?


The in-between days. During November’s listening periods with the Red Wine Audio Signature 57 I played a frequent switcheroo between it and a pair of Wyred4Sound mAMPs. With the RWA intergrated packing its own volume control I’d run the Resonessence Labs INVICTA Mirus DAC source-direct into the the Californian Class D monoblocks. No need for a pre-amplifier when running this DAC’s digital volume in the upper-quartiled safety zone, where word-length truncation doesn’t eat into the music.

In the Red Wine coverage I likened Wyred4Sound minis’ sound to that of a high-quality vodka with a hint of peach; the subtle fruit infusion being indicative of EJ Sarmento’s ability to sidestep the reputation established by the earliest ICEPower implementations: needlepointy on detail delivery, cooler on tonal colouring and a starchy on aftertaste. If anything, Sarmento’s mini range, that includes the mINT integrated, display occasional shades of humidity and tenderness. Note: I’m purposefully avoiding ‘tubey’. The mAMPs pull way ahead of the mINT with transparency on upstream changes; they’re a reviewer’s dream ticket.

However, my first taste of a source-direct setup wasn’t as enjoyable. It arrived courtesy of Bel Canto in 2010 when I ran an eOne DAC 3 D/A converter directlty into a S300 power amplifier. The results were underwhelming: thin, reedy and barely enough juice in reserve for the (admittedly thirsty) ATC SCM 11. After a week of trying to acclimatise to this new sound, I returned the power amp and took an S300iu integrated in its place. Much better! Tonal mass and drive returned to the picture. Remember tonal mass – we’ll be coming back to it.

Three years down the line and I’m once again immersed in a similar setup. The question simmers: with volume-attenuating DACs so prevalent, do we still need traditional pre-amplifiers?

The digital audiophile is being encouraged to ditch his traditional pre-amp to save on dollars and interconnecting cables. Source direct is close(r) to the oft-touted nirvana of a ‘straight wire with gain’. Whatever your take on that ideology, the argument for running a DAC direct into power amplification, circumventing the pre-amplifier altogether, makes intuitive sense. Why run with more boxes and/or gain stages than the minimum required? Less IS more. William of Ockham, he of Occam’s Razor, would no doubt approve: “Entities should not be multiplied unnecessarily”.

Let us pause for thought. The role of the pre-amplifier is three-fold. ‘Passive’ pre-amplifiers handle source selection and volume attenuation. ‘Active’ designs stir a gain stage into the mix. Pre-amplifiers can also step-in to resolve impedance mismatches. If the output impedance of the source is (comparatively) high there will be incompatibility issues with some power amplifiers. This can result in ill-defined bass, vague imaging and rolled off highs. Pre-amplifiers have the potential to resolve such issues.

There’s no doubt that the pot-less Metrum Hex requires pre-amplification. Ditto AURALiC’s Vega. Wait, wut? Yes, when lassoed to the Wyred4Sound mini monos the Vega gives up reasonable SPLs in the lower third of its volume range. Alas, this is where the least significant bit truncation of digital volume control eats a hole in musical information, the soundstage shrinks and tonal mass loses more weight the lower you go. AURALIiC co-founder Xuanqian Wang concedes: “If you are running mostly below 30 for serious listening, I would recommend a high quality pre-amplifier.”

Resonessence Labs INVICTA Mirus is another of the many modern DACs to pack a volume control into its feature set. Thankfullt, it runs well into the upper third of its volume range, especially when the W4S monoblocks are direct-connectied to the lower voltage (2.3V) single ended outputs. Throughout the latter half of this year I’ve run the INVICTA Mirus RCA-to-RCA into the W4S twins more frequently than any other combination. It’s a combination that has become a bit of a 2013 reference.

Each Wyred4Sound mAmp features a FET input buffer with a suitably high 100 kΩ input impedance whilst the output impedance of the INVICTA Mirus is a suitably low at 39 Ω. No impedance mismatch concerns here! Long cable runs can excacerbate impedance woes but, again and for emphasis, no problems here: I used one metre lengths of Zu Audio single-ended interconnects. Results were checked and double-checked with one meter XLR-terminated wires from Grave Science.

In isolation, I had zero complaints about the sound mined by Resonessence Labs’ flagship DAC and the Wyred4Sound monos…but I was curious: would an intervening pre-amplifier bring anything to the table? Rather than dropping something price commensurate into the chain, I went large. I pushed deep into the high end: YBA’s Passion Pre500 retails for AU$10425. If there were no gain (pun intended) to be had from this $10k ‘active’ pre, game over.

Prior to relaunching the brand in mid-2012, YBA’s French designer Yves Bernard André had been laying low for a couple of years. Financial and marketing muscle now comes from Chinese parent company Shanling. The Passion Pre500 is a beautifully engineered box. Heavy too. The elegantly fashioned remote control underscores YBA’s aesthetic elegance. However, this isn’t a review of the YBA itself. It’s a short investigation into product type relevance.

With the YBA turning the original trio into a quartet, the deltas were startlingly obvious from the very first push of play.

Firstly, the YBA built the soundstage bigger. MUCH bigger. In ALL directions. Secondly, detail retrieval went deeper, most clearly reflected in the greater grip of gut on string with the cello and double bass that drive forward the sinister swagger of Angelo Badalamenti’s “The Pink Room” (from Twin Peaks: Fire Walk With Me OST).

The sparkle of low level super-micro dynamics within the depths of A Sagittariun’s “Crystallization” made for a more vivid take on hyperreality. In fact, it had me wondering if the matching YBA Passion 650 power amplifier might counterbalance the increased brilliance of Skittle-ish tonal colours. If you’re looking for a listening experience that you can sink into like an old armchair, the YBA’s amelioration (in the context of Wyred4Sound monoblocks) might not be for you.

Lastly, the YBA Passion Pre500 fleshed out tonal mass (but not as much as I’d expected). This meant more metaphorical muscle and fat on top of the lean-ish – but emphatically not skeletal – frame already formed by the Resonessence Labs D/A converter. Picture a lean long-distance runner carbing up to become a 200m sprinter.

This all points to the pre-amplifier holding tight to sonic relevance, even in systems fronted by a volume-controlling DAC. There’ll be more to come on this when I swap out the YBA pre for Wyred4Sound’s mAMP-matching mPRE in a day or so. Hang tight y’all.

Further information: Wyred4Sound | Resonessence Labs | YBA

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
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  1. Hi John

    Interesting how we have different experiences. There is only one DAC I know that wasn’t improved by direct connecting in my system. That was the Playback Designs because of it’s high output noise that needs attenuating in the pre – and even then only for amps that you had to use a lot of attenuation with because they are very sensitive.


  2. I recently has the same experience as you JD but in reverse, when giving up my Densen B200 pre-amp to go DAC direct. Something is missing detail and soundstage wise.

    I think its not just because a DAC truncates the bits for volume control, but also because these DAC’s use op-amps for the output stage, compared to a good pre-amp that uses a discrete output stage.

  3. John, this has been my experience exactly! After trying DAC-as-pre, for many years (the best of which, was the original EE Minimax); I just found good, active pre-amps…fleshed out the sound, and rounded out the presentation in a much better way.

    I think the issue is 3-fold; digital volume, (possible) impedance mismatch, and gain itself. But I’m curious…how do you think the Mytek’s analog volume would fair?

    • The Mytek’s analogue control means it behaves like a passive pre. It sounded a little better than the digital volume control but, again, I suspect an active pre would flesh things out further. One thing I should also mention: going DAC direct might be leaner but there’s a slight lift in perceived quickening.

  4. Interesting topic. I have recently bought an Ayon CD-3s (very versatile bit of kit) because it answers many needs both new and old. I’m fickle, still listen to those flat plastic things and the flat silver ones too, as well as other digital sources, and the Ayon makes a nice fist of the latter two – with the addition of a little well implemented tube goodness. I tried running it direct to a Mod Wright power amp but to my ears it still benefits from the addition of a pre. This despite the fact that the volume on this beasty (it’s big!) is handled entirely in the analogue domain. I find if I use the variable volume mode on the Ayon and throttle back a bit (fixed volume mode is default to max) the pre breathes more easily with it’s volume pot opened up, adds more tonal flesh – and just a touch more warmth oddly enough – despite it’s SS architecture. I really hadn’t expected that result. But then, when do we ever get what we expect in the world of hi-fi? Look’s like I’ll be keeping a pre for a while yet.

  5. John, the idea that as long as you use digital VC in the upper end of its range it becomes “transparent” is simply a fantasy. It’s something that makers of relatively inexpensive DACs like to push so that they can add another feature box to tick compared to their competitors which may not offer a volume function. “No need for a pre-amp!” BS.

    There’s only one way to get away with not having a pre-amp, and that’s an integrated amp. Integrated amps used to be the entry level stuff you left behind as soon as you could afford proper separates, but that’s not the case anymore, not when there are products like the Vitus SIA-025 and Accuphase E-600. Provided you are using relatively efficient speakers in a relatively modest space, these pure Class A integrateds are not that different from their respective companies big gun Class A power amps. Their volume controls also use trickle down tech from their ultra high-end line-stages. The last thing they would use is digital VC.

    The Accuphase *does* potentially offer the ability to eliminate a separate DAC though, thanks to the optional DAC board.

    This raises an interesting question. What’s better, a $3,000 DAC with digital VC, or a $3,000 “DAC/Pre” line-stage with a built-in DAC board?

    • That very question I’m investigating this weekend.

      The notion of ‘transparency’ *might* indeed be fantasy but one must consider the ability of the associated components’ ability to resolve any degradation at the upper end, where resolution loss is far smaller than at the lower end of digital attenuation scale where it is more easily *audible*.

  6. I’ve also found that the traditional (active) pre-amp can play an important role but struggle as to how to take advantage of digital EQ (even for an all digital system). It’s possible, of course, to do EQ at the source but this becomes an issue if one has multiple sources. Meanwhile, digital EQ after the pre-amp introduces additional A/D/D/A conversion as well as issues at low volumes. All in all it seems as if the answer is a DAC with in-built EQ facilities.

  7. I run a metrum acoustics octave dac, a audiocubics volumecontroller with remote and two active adam artist 6 boxes. I can regulate bas treble and volume to at the speakers. The sound is excellent. So I do not need a extra box with a preamplifier in it, but plenty of dealers will not tell you so.

  8. What do you think of the CADs ( preferred methodology – i.e. using the volume control in audirvana on a MacBook Pro, they run the dac direct into a power amp…i.e no preamp?
    Will this preferred method for CAD (TD1543 NOS) DAC work with a Metrum for example, and if so can you give this topology a shot John, let us know your feedback?

    • Sure, it’s possible with the Metrum but I’m not game enough for software volume control direct in a power amp. One erroneous slip and your drivers are toast. I heard of one such fellow recently doing exactly that to a pair of KEFs: he left Audirvana+’s volume control on full, hit play and bang (!), all up in a puff of smoke.