Thursday, 13 November 2014

The PS Audio DirectStream DAC - Part IV.

It has been several months now since I concluded my review of the PS Audio DirectStream DAC, and a pretty positive review it was.  Since that time the unit has continued to very gradually break in, and there have also been a couple of firmware updates (all of which are available on PS Audio’s web site at no charge), each an improvement, but not sufficient to justify adding substantially to the gist of my review.  But recently there has been a major firmware update - version 1.2.1 is its designation - which is a sufficient game-changer that it warrants a whole update of its own.

So why should something as perfunctory as firmware change the sound of a DAC?  Normally when we think of firmware updates we think of functionality rather than performance.  And indeed there are functionality issues which are addressed here - the DirectStream now fully supports 24/352.8 PCM, which it did not do with the original firmware.  But in a DAC in particular, a large part of what it does performance-wise lies in the processing of the incoming data in the digital domain, and those processes are often under the control of the firmware.  Particularly in the DirectStream, where all that processing happens on in-house PS Audio firmware rather than within the proprietary workings of a third-party chipset.  What goes on under the aegis of its firmware is to a large degree the heart and soul of what the DirectStream is all about.

I have communicated at length with Ted Smith, designer of the DirectStream, about the nature and effect of the changes he has made.  I’m not sure how open those discussion were intended to be, and so I will not share them in detail with you, but there are two areas in which his attention has been primarily focussed.  The first is on the digital filters, and how their optimal implementation is found to affect jitter, something which initially surprised me.  The second is on the Delta-Sigma Modulators which generate the single-bit output stage, always an area ripe for improvement, in which Ted has reined in the attack dogs which stand guard to protect against the onslaught of instabilities.  Together, the effect of these significant updates has been transformative, and that is not a word I use lightly.

The simple description of the sound of the 1.2.1 firmware update is that it has opened up the sound.  Everything has more space and air around it.  Sonic textures have acquired a more tactile quality.  The music just communicates more freely.  It would be easy to sit back and characterize the sound as more “Analog-” or “Tube-” like.  These are words the audiophile community likes to use as currency for sound that is quite simply easy to listen to.  It is interesting that we audiophiles admire and value attributes such as sonic transparency, detailed resolving power, and dynamic response, and yet how often is it that when we are able to bring them together the result is painfully unlistenable?  It is these Yin and Yang elements that are foremost in my mind as I listen to the 1.2.1 version of the DirectStream.

So, without further ado, what am I listening to, and how is it sounding?

First up is “Bending New Corners” by the French jazz trumpeter Erik Truffaz.  This is a curious infusion of early-‘70s Miles Davis, ambient groove jazz, and trip-hop, which brings to mind the sort of music that might have deafened you in the über-trendy restaurant scene of the 1990’s.  I first heard it on LP at the Montreal high-end dealer Coup de Foudre, and today I’m playing the CD version.  The mix is a relatively simple one involving trumpet, bass, keyboards and drums, plus the occasional vocal stylings of a rapper called ‘Nya’.  The music is set in an atmospheric ambient, and is quite simple in its sonic palette, but nevertheless I have always had trouble separating out the individual instruments.  I was keen to know what the additional resolving power of the 1.2.1 DS would make of it.

What the additional clarity brought was the realization that I have been hearing the limits of this recording all along.  The trumpet has a very rich spectrum of harmonics which overlay most of the audio spectrum, and when it plays as a prominent solo instrument those harmonics can intermodulate with the sounds of many other instruments, making it difficult to hear through the trumpet and follow the rest of the mix.  If the intermodulation is baked into the recording, then no degree of fidelity in the playback chain is going to solve that problem.  This is what I am plainly hearing with the 1.2.1 DS.  This recording, far from being a clean and atmospheric gem waiting for an extraordinary DAC to liberate its charms, is a bit of a digital creation.  The extraordinary DAC instead reveals its ambience as a digital artifact.  The lead trumpet and vocals can be heard to have a processed presence about them.

Once you have heard something, you can never “un-hear” it again.  It’s a bit like skiing, in that once you’ve mastered it, it becomes impossible to ski like you did when you were still learning.  At best, all you’ll manage is a caricature of a person skiing like a novice.  I can now go back to the CD of “Bending New Corners” on a lesser system and will recognize its flaws for what they are, even though previously I would have interpreted what I was hearing differently.

My experience with Bending New Corners was to be repeated many times.  As I type, I am listening to Ravel’s Bolero with the Minnesota Orchestra conducted by Eiji Oue on Reference Recordings, ripped from CD.  It begins with a pianissimo snare drum some 20 feet behind the speakers and slightly to the right of center.  This recording has always been one of which I have thought highly.  The solo pianissimo snare is a good test for system imaging.  However, I now hear the snare as living in a slightly smeared space.  I perceive its sonic texture differently - more plausibly accurate if you will (a layer of sonic mush hovering around the instrument itself has evaporated away like the early mist on a spring morning) - but I somehow cannot place the image more accurately than a few feet.  I surmise that, because my brain is more confident that it is hearing the sound of a pianissimo snare drum, it therefore also expects to hear that sound more accurately localized in space.  But it is unable to do that.  As a consequence, although I never previously thought that the stereo image was wanting, I now appreciate that in fact it is, and I wonder how a higher-resolution version of this recording would compare.

Here is a song my wife likes.  It is “Hollow Talk” from the CD “This is for the White in your Eyes” by the Danish band Choir of Young Believers.  My wife had me track it down because it is the theme tune on a Danish/Swedish TV show we have been watching on Netflix called The Bridge (Bron/Broen).  It is another example of how the DS 1.2.1 can render a studio’s clumsy machinations clearly manifest.  The echo applied to the vocal adds atmospherics but is just unnatural.  As the track proceeds, the production gets layered on and layered on - and then layered on some more.  The effect is all very nice when heard on TV, but on my reference system driven by the DS 1.2.1 it just calls out for a lighter touch.  For example, at the beginning I heard a faint sound off to the left like someone getting into or out of a car and closing the door.  I don’t see why they wanted to include that - I can’t imagine it is particularly audible unless you have a highly resolving system such as a DS 1.2.1, one which makes clear the dog’s breakfast nature of the recording.

Next up is another old favourite of mine, “Unorthodox Behaviour” by 1970’s fusion combo Brand X.  I saw the band live at Ronnie Scott’s club in London back in 1975 (or thereabouts) and bought the album on LP as soon as it came out.  Today, I’m playing a 24/96 needle-drop.  I just love the opening track, Nuclear Burn.  Percy Jones’ bass lick is original and memorable, and extremely demanding of technique.  DirectStream 1.2.1 lets me hear the bass line more clearly than I have ever heard it before.  I had always thought it to have a slightly muddy texture - not surprising, given that playing it would tie most people’s fingers into inextricable knots - but now I hear just how extraordinarily skilled Jones’ bass chops really were.  And below it, Phil Collins’ kick drum has acquired real weight.  Not that it sounds any louder, or deeper.  It is more like the pedal mechanism has had an extra 5lb of lead affixed to it.

Now to a lonely corner of your local music store, where the Jazz, Folk, and Country aisles peter out.  This is where you’ll find Bill Frisell’s 2000 CD “Ghost Town”, a finely recorded ensemble of mostly acoustic guitar and banjo music with Frisell playing all the instruments.  Despite the album’s soulful and contemplative mood, due at least in part to the sparse arrangements and absence of a drum track, I keep expecting it to break out suddenly into 'Duelling Banjos'.  The track list comprises mostly Frisell original compositions together with a handful of well-chosen covers.  Apart from enjoying the music, the idea here is to play Spot The Guitar.  On a rudimentary system this involves telling which are the guitars and which the banjos.  As the system gets better, you start to be able to tell how many different models of each instrument are being played.  With the DS 1.2.1 I suspect you could go further and identify the brands (Klein, Anderson, Martin, etc.).  Me, I’m not a guitar head, and can’t do that (although, back in the day, I used to be able to reliably tell a Strat from a Les Paul, even on the most rudimentary systems), but I do hear the different tonalities and sonorities very clearly.

Gil Scott-Heron is credited in some circles as being the father of rap.  He was a soulful yet extremely cerebral poet-musician with a strong sense of a social message.  His 1994 CD “Spirits” was a bit of a swan song, and contains a track “Work for Peace” which is a political rant against the 'military and the monetary', who 'get together whenever it’s necessary'.  I kinda like it - it is, I imagine, great doper music … yeah, man.  But the mostly spoken voice is very soulfully and plausibly captured.  You can imagine the man himself, in the room with you.  I would just love to hear the original master tape transferred to DSD.

I Remember Miles” is a 1998 CD from Shirley Horn.  It’s a terrific recording, and won the Grammy for Best Jazz Vocal Performance.  But really, it is an all-round wonderful album.  And the standout track is an absolute classic 10-minute workout of Gershwin’s “My Man’s Gone Now” from Porgy and Bess.  It begins with Ron Carter’s stunning, ripely textured, ostinato-like bass riff which underpins the track.  It has always sounded to me like two basses - one electric and one acoustic - but with the latest DS 1.2.1 the electric bass tones now sound more and more like an expertly played and finely recorded acoustic bass, and in addition I’m beginning to think there’s just the one bass - perhaps even double-tracked.  I’d love to know what you think.  Aside from the tasty bass, the rest of the recording is revealed to have a smooth but slightly congested, slightly coloured sound, a bit like what I hear when I listen to SETs played through horn speakers (I know, I know, heresy.  Kill me now.).  The immediacy and sheer presence of a fine DSD recording is just not there.  Unfortunately, this has not been released on SACD either.  Perhaps a DSD remaster will finally put the bass conundrum to bed?

Which brings me to the nub of this review.  Finally, the DirectStream is delivering on its huge promise as a DSD reference.  With the 1.2.1 firmware, it is opening up a clear gap between its performance with DSD and PCM source material, along the exact same lines as my previous experience with the Light Harmonic Da Vinci Dual DAC.  The DSD playback just adds that extra edge of organic reality to the sound.  It just sounds that little bit more like the actual performer in the room with you.  Sure, CD sounds great on it - probably as good as I’ve ever heard it sound - but the DS 1.2.1 consistently shows CD at its limits.  Great sound requires more than CD can deliver across the board, and in my view the DS 1.2.1 - through its excellent performance - makes this about as clear as it’s ever going to be.

In Part II of my review I mentioned the CD of Acoustic Live by Nils Lofgren.  I recently came across a SACD of music from the TV series “The Sopranos”, and it contains “Black Books” from the Lofgren album.  The CD is a pretty special recording, but the DSD ripped from the SACD just blows it clean out of the water, if you can imagine such a thing.  The vocal has incredible in-the-room-in-front-of-you presence.  All of the acoustics, which were already pretty open, really open up.  The pair of tom-toms I mentioned take on individual tonality, texture, and weight.  And the guitar work, which I previously characterized as being 'aggressively picked' comes across with a much more natural and plausible sound.  You just cannot go back to the CD and hear it the same way.  DAMN!  Someone needs to release this whole album on SACD, and preferably as a DSD download.

Another great SACD is MFSL’s remastering of Stevie Ray Vaughan’s “Couldn’t Stand The Weather”, with its perennial audiophile favourite “Tin Pan Alley”.  Beginning with a solid kick drum thwack, it launches into a cool, laid-back, 12-bar blues.  Vaughan’s guitar has just the right combination of restraint and blistering finger work, and his vocal is very present and stable, just to the left of centre.  The rhythm section lays down a fine metronomic beat, playing the appropriate foundational role upon which SRV builds his performance.  By contrast, in their uncomplicated take on Hendrix’s “Voodoo Chile”, the drums are given full rein to pound out a tight and impactful rhythm, and SRV gives his guitar hero chops a good airing.  If you’re unfamiliar with SRV and want to know what the man was about, this would be the place to start.  It is a fantastic recording, and one that has been expertly transferred to SACD.

The Japanese Universal Music Group has remastered and released many classic albums in their SHM-SACD series, all of which are both hard to come by outside of Japan, and ruinously expensive.  Their work on Dire Straits’ “Brothers in Arms” is interesting.  To the best of my knowledge the original recording was on 20-bit 44.1kHz digital tape (but there are people around that know more than me about those things).  Anyway, the fact is that there is no obvious reason why a remastered SACD should sound significantly better than the original CD, unless, of course, the latter was not well mastered.  However, the conventional wisdom is that Mark Knopfler was particularly anal about the recording and mastering quality, and so maybe that argument doesn’t hold water.  Additionally, the Universal SHM-SACD can be compared with a contemporary remastering by MFSL, and both can be compared to the original CD.

Right away, both SACDs come across as superior to the CD in all the important ways.  The title track, Brothers in Arms, is one of my all-time go-to tracks.  On both remasterings, with the DS 1.2.1 the vocal has that signature SACD presence, and Knofler’s guitar work sounds more organic, more like a real instrument in the room with you - just like with the Nils Lofgren.  I puzzled over how and why two SACD remasters from impeccable digital sources could sound different.  But they do, and maybe someone could enlighten me about that.  The two remasters sound almost stereotypical (there’s gotta be a pun in there somewhere) of how we think of Japanese and American musical tastes.  The Japanese SHM-SACD is massively detailed, but with slightly flat tonal and spatial perspectives compared to the American MFSL.  The latter’s tonal bloom fills the acoustic space in a more immediately appealing manner, but at the apparent cost of some of that delicious detail.  If one is right, then the other must be wrong, so they say.  You pays your money, and you takes your choice.  But the bottom-line is that with a DAC of the resolving power of the DS 1.2.1 considerations such as these are going to weigh more heavily than might otherwise be the case.

So there you have it.  The 1.2.1 firmware update will transform your DirectStream from a great product into a game-changing product.  I concluded my last review by comparing the DirectStream, with its original firmware, to my all-time reference, the Light Harmonic Da Vinci Dual DAC.  I felt that, based on my aural memory, since I no longer have the Da Vinci to hand, that the DirectStream was not quite up to the latter’s lofty standards.  With the 1.2.1 firmware I am no longer so sure about that.  I would need to have both DACs side-by-side in order to be certain.  But this time around my aural memory tells me that the DirectStream in its 1.2.1 incarnation could very well give the Da Vinci a good run for its money.  And in some areas, such as its bass performance, I even wonder if the DirectStream might not come out on top.  Let's bear in mind the price difference - $6k vs $31k.  That’s an extraordinary achievement.