Audiophilleo USB/S/PDIF Converter

An Audiophilleo for the Audiophile



At the initial gathering of “The Hoodies,” six or seven ill-dressed future quadrillionaires, none of whom had ever even casually flipped through a copy of GQ at their local news stand, peered out from behind a gaggle of black plastic coke-bottle eyeglasses (the kind with the white tape in the middle), and giggled giddily amidst piles of empty Cheetos bags.  Fueled by half-drunk six-packs of Red Bull (or by whatever sacchariney-sweet energy drink techies and bungee-jumpers guzzled back then), they incubated their embryonic plans for the world domination of USB.  We, the audiophile multitudes were powerless to stop their caffeinated concatenations.  We never even got the Evite.

USB signal transmission was definitely not designed with us in mind. To wit, Wikipedia reads: “USB was designed to standardize the connection of computer peripherals (including keyboards, pointing devices, digital cameras, printers, portable media players, disk drives and network adapters) to personal computers, both to communicate and to supply electric power.”  Curse those casually attired (though no doubt comfortable) bastards!

No mention whatever of soundstaging, imaging, inner detail or PRaT.  And now in 2013, USB (Universal Systems Bus) gets into all the hottest clubs.  It’s everywhere - and we’re not invited.

What to do… what to do?  Especially since computers themselves, once regarded askance by real ‘philes, have now become de rigeur for everyone except Marty De Wolf (Bound For Sound) and of course, Harry Pearson. 

And the software authors whose intricate coding helps us ring every last significant bit out of our Mac Mini’s are revered — memorialized in song and dance. Oh great Damien of Audirvana  — thank thee, thank thee—ohhhhh thank thee! No seriously—thank you Damien.  It’s good stuff! :)

You get the idea. The revolution was already televised and CD players are the new 8-track cassette.  But don’t worry- if history serves, they’re just going on brief hiatus, only to be back atop our consoles in like 20 or 30 years.  Do NOT throw away that Brittany Spears Toxic CD!  That little silver disc is gonna be worth thousands of... bitcoins (?) in like twenty years! 


USB “converter” boxes, whether $99.00 or $22,000 (I’m almost sure there’s one for that much- I’m almost sure…), “clean up”the USB signal in essentially two ways prior to passing it along via S/PDIF cable to your digital converter of choice; firstly, by filtering out some of the electrical noise your computer may be transmitting on to your DAC owing to the former’s “dirty-by-audio-standards” power supply and secondly, by de-jitterifying the USB signal.

Now - in addition to being an oft injured Yankees shortstop with a $10,000 dollar a week Victoria’s Secret model habit (I’m estimating… dinner...drinks…a movie), jitter, as every audio person knows, is the timing artifact in the digital signal which when unchecked, can lead to wiry sounding string quartets, (more) strident sopranos and in extreme cases, may cause Metallica’s “Enter Sandman” to sound like a poorly performed rendering of the second act of Vincenzo Bellini’s little known opera “Il Pirata.” Now that’s jitter! 

If you need more motivation than this to employ a USB converter in your seestem, allow me to add that many computers don’t come standard with an S/PDIF output and many digital converters which are USB capable—really are not.  By this I mean, connecting your computer with even a slick, fat, purple $1,000 dollar USB cable directly to your USB “capable” DAC will often result in a substandard Derek Jeter-y signal transmission and there ya go—you’re nearly through the entire first act of Il Pirata before you can say “Lars Ulrich.”

It stands to reason then that a “better” USB converter, like a “better” power strip, would be better at cleaning up the signal from your computer, while allowing the non-noisy parts of said signal safe passage.  And that’s pretty much (shocker) how it went down.


One Dedicated Converter

It seems all the affable Phillip Gruebele of Audiophilleo does in (professional) life is make USB converters in various iterations, so I’d say he should have a serious inferiority complex and equivalently dire need for psychotherapy and/or Scientology auditing if some not so specialized company were to ‘win’ this particular beach volleyball game. 

Sez Philip, “A few years ago I looked into USB to S/PDIF converters and did not like how they sounded or how they were designed. Everyone seemed to copy 30 year old technology when designing their S/PDIF output stages. I decided to apply design principles from modern communications systems instead. Hence the transformer-less output stage which differentiates the AP products. Isolation is not implemented via the usual output transformer. This architecture also lends itself well to better dc and ac noise isolation between USB and DAC when used with the PurePower [battery power pack upgrade on my review model]. This is why the PurePower makes such a substantial difference in sound.”

Myself, I’ve been kind of slumming it for years with the original Musical Fidelity V-Link. Okay so it’s the V-Link II, but the II is almost identical to the original outside and in.  Well, the V-Link II is a bargain priced product but, like a great $1,500 6” two-way standmount, it will certainly give you a glimpse of what the more rarified members of its genre are capable of.

In fact, even in the case of the DAC inside the relatively high tech Burson Conductor headphone amp atop my console, Audirvana’s latest version ( playing music via my Mac Mini with the V-Link in the chain somewhat outperforms the Conductor DAC directly connected.  The Burson Conductor DAC gets closer to not requiring a converter in the chain than any other USB capable DAC I’ve used, though still — not quite a cigar as compared with a “cheaper” USB converter.  Via the V-link, the main thing I can discern is that there’s is a bit more space when it’s on the recording and a bit more detail as well.   Surprisingly, bass is a pretty close race.  In fact, on my initial hearings, the “unconverted” Burson almost convinced me my V-Link wasn’t needed anymore.  It took a few days of intermittent switching back and during the Conductor review for the V-link to convince me it would not be needing its golden parachute severance package just yet.

The Audiophilleo with PurePower is better.  I know - you’re shocked.  It’s less spatially challenged and has a “denser” presentation.  Music has a bit more emotional pull and hits harder.  There is certainly more detail on offer all around, particularly as concerns the top end, which is noticeably more detailed and less ‘mechanical’ with no hint of edge (except when called for, of course). Even still, we are not night and day, $200.00 speaker vs. Wilsons different here.  It’s not like the V-Link II is terrible; only that its deficiencies are more easily seen when sunning itself in the glow of a superior product. 

Now I also had on hand my very own more upscale and more recently acquired Halide Bridge converter, which thankfully enabled a closer Whole-Foods-organic-apples-to-apples comparison. The beloved24/96 capable (get with the times! We’re at like 384 or something now!) Halide Bridge converter retails for $399.00 period. No black market, no middle-man and no negotiation required.  No upgrade options available either.  Essentially - It’s a friggin’ USB cable running into a black plastic dongle with an RCA connector on the end.  The “Streamlength” algorithm in the little dongle (careful here...) it uses for digital conversion is apparently one licensed from computer audio guru/spiritual guide Gordon Rankin of Wavelength Audio fame.

It’s only fair to point out the AP PurePower battery pack mod alone adds $479.00 to the Audiophilleo AP1’s base price of $999.00 and the company specifies that when connected, “it powers only the sensitive clocks and output stage through an additional power connector, providing the lowest possible noise. The USB ARM processor continues to be powered from USB.”  FYI, once your Audiophilleo is PurePower enabled, you can’t listen to it without the PurePower connected.   So I was unable to do perhaps the closer comparison; the non PurePowered AP with the Bridge. Eh— se la vie.  Then you die.  Fortunately, Audiophilleo’s AP2 comes in at only $579.00, and while less feature packed than the AP1, also allows the addition of the PurePower and is, according to Phillip at AP, sonically indistinguishable from the AP1; it just lacks the latter’s feature set, i.e. digital display, digital volume capabilities etc. 

Speaking of features, I should mention that the Audiophilleo AP1 converter itself isn’t just a converter.  It’s also a lossless dithered volume control with a nifty numeric and color bar display to indicate level and here’s my favorite feature:  it can cleverly simulate for you with the click or two of a tiny black button, what jitter in your system would actually sound like by introducing it back.  (Hint:  not better).   This simulated jitter is also a nifty way to prove to your significant other that your $1,400 some dollars did not die in vain. Moreover, in addition to coming standard with 24/196 kHz capability, the AP I is also now available with optional 384 kHz and DSD capability for an extra $150 bucks which works beautifully when listening to those two Diana Krall albums that currently require it. (Sorry—is it three now?)

By the way, along the lines of the AP1, the PurePower module itself isn’t just a slab of battery.  Like Vinnie Rossi’s gear, it’s a “smart” battery with 15 hours of play time (enough for the Ring cycle plus those two high-res Diana Krall albums back to back) and then it auto-charges when you’re done playing music. Neat!

“…the meaning of an episode was not inside like a kernel but outside, enveloping the tale which brought it out only as a glow brings out a haze.” -Joseph Conrad

The Halide Bridge/AP I PurePower comparison highlighted for me once again the importance of system synergy.  To me, the Metrum Octave non-oversampling DAC I own has always sounded gloriously organic, albeit a bit less detailed on top (and maybe even in general), by way of comparison with the equally glorious Burson Conductor DAC.  I believe it was this difference in presentation that lead me to slightly prefer the API PurePower when listening via the Metrum. 

The more finely detailed and dense AP complimented the slightly warm Metrum beautifully and may have served as a very slight equalization such that I felt I was hearing all the Metrum could give me to hear.  Via the Bridge, I got the sense at times that the ‘brightness’ dial could do with an eighth twist or so, to bring back a touch of “sparkle,” particularly as concerned coloratura sopranos or maybe a solo violin.  This was not the kind of thing I was constantly aware of.  It was only apparent when switching to the AP1 from the Bridge and re-listening to the self-same track.  Otherwise—I could be happily crashed out on the couch listening to either converter.

Similarly but differently, the AP1 with the Burson Conductor really tells you everything you need to know about whatever recording you want to know it about.  It is not a clinical sound- never too bright or anything unless the recording is - but it is accurate.  You really hear the recording artifact on old Enrico Caruso recordings and you get all of the gleam and glint on the top notes of my 1970 and 1980’s Pavarotti recordings.  There’s this edit I can hear on the aria I Puritani, Act One: "A Te, O Cara” from the Pavarotti recording King of the High C’s [London] and I always hear it with a decent system. It’s right in the middle of legato phrase.  I heard it more blatantly than I would ever need to via the Burson/AP1.  The Bridge seems to veil it just a hair more.  It’s never bothersome—just apparent.  And it’s a good indication of my overall sense of the AP1.  I feel it may be more “true” to the original recording than the other two converters, but there is no sterility.  As I say, it also doesn’t “brighten” anything. It just allows the tonal qualities of my gear to present themselves in unadulterated fashion. 

Listen, we are talking Graphene cables here (one atom thick).  The Bridge and the AP1 are both forget-about-them-and-listen-to-music good.  It’s just there are small differences and I feel those differences mean the AP1 is the more “accurate” converter in the same way the Burson Conductor DAC may be more “accurate” (linear?) sounding than the Metrum.  This to me makes sense financially, as those people in the market for an $1,100 USB converter may have more ‘high end’ systems than the guy buying the Bridge (maybe?) and will want to hear every last rosiny glint their $20,000 Magicos can show them. 

But while the AP 1 was slightly more detailed and perhaps displayed more sheer “density” in the image (more apparent to me with recordings of multiple singers in a theater or with solo voice), I don’t really feel it was leaps and bounds more musically enjoyable than the Bridge- but perhaps it was mildly so.

Myself?  If I could afford it, I would probably go for the AP 1 plus PurePower (wish I coulda compared the PurePower AP to the non-PurePower AP — maybe next time).  The improvements in sonic detail and density, sky-high kHz decoding capability (love those two or three Krall albums!) and its lack of need for a coax cable, plus its ability to serve as a lossless digital preamp along of course with the pretty dancing volume lights, really do make a strong case for audiophile lust.  But when the AP1 and her little battery pack go back to their maker Phillip Gruebele, I won’t exactly be in mourning with the Bridge. 

Perhaps I would light some candles if I were left solely with the V-Link.  But... in my defense, I’d wear black for a week or two, have a cry with my good girlfriends over a pint of Chubby Hubby, update my Facebook status to “Without Converter” and then get over it. 

Bottom line—if you can afford it and really want to hear everything your seestem is capable of, I’d go for the AP1 plus PurePower.  It seems somewhat truer to the source.  You can even sell your current digital cable to help pay for it, as the AP1 direct connects to the back of your DAC—no cable (or cable jacket) required. Just be sure before you get the credit card statement, that you know how to use your AP1’s simulated jitter mode.  That way, once your financial advisor/significant other hears what digital jitter sounds like when unchecked, they’ll definitely get why you just spent $1,400 on two small metal boxes with dancing, multi-colored lights. Especially if they are no fan of composer Vincenzo Bellini - Definitely then.


I bid you peace.


Price: Audiophilleo AP1: $999.00

PurePower battery pack $479.00 


Display: 1.7 inch (43 mm) diagonal, 262K Colors, 160x128 pixel resolution (Audiophilleo1)
Dimensions: 3 x 2 x 0.75 in (76 x 51 x 19 mm)
Weight: ~ 4 oz (113 g)
Space required: 15cm of space is required behind the DAC BNC/RCA tip. Right angle adapters can be used to reduce this space.

Sample rates

24 bits at 44.1, 48, 88.2, 96, 176.4, and 192 kHz. 16 bits at 44 and 48 kHz is also supported for iPad compatibility. Note that to the DAC, 24 and 16 bit S/PDIF data look the same, so it does not matter whether you play a 16 bit audio file in 24 or 16 bit mode. All devices support DSD64 over DoP. The Audiophilleo1 Special Edition additionally supports 352.8 and 384 Khz sample rates and DSD128.