by John Grandberg

Computer Audio. Do you shudder at the term? Is it a confusing, murky category that you don’t fully understand? Do you read show reports and sense the inevitability, like you had better figure it out sooner than later? As CD sales continue to decline and more companies embrace some type of file-based playback, the computer audio category is becoming difficult to ignore. The theory goes like so: one of these days in the near future, all of our playback will come from a computer. New music will be acquired online, sidestepping that whole “physical media” thing. Casual listening will come from services like Spotify, Rdio, and numerous internet radio stations. CDs? Those will gradually be phased out, relegated to obscurity in local shops which cater to the rare customer wanting physical media with the brick-and-mortar experience.

Do I buy that? Maybe. Depends on the time line I suppose. It definitely won’t happen overnight. If we’re talking about maybe 10 years from now then yes, I do see the download market taking precedence. That’s assuming it isn’t replaced altogether by streaming services … which some contend will be the case. In my version, you’ll have iTunes and Amazon for the masses, with HDtracks, iTrax, 2L, Acoustic Sounds, et al for the rest of us. The players may change but the concept will be the same. As of 2012, CD sales were still quite a bit higher than digital album sales, though maybe it’s a flawed comparison. Do people even buy entire albums on iTunes these days? Digital downloads of individual songs were very high, and CD singles must not be a hot item as Nielsen Soundscan apparently doesn’t even track those. It’s not all roses though — 2013 showed a decrease in digital music sales. The theory is that people did more streaming and less actual downloading of purchased music. CDs continue to decline but so far have not been surpassed by downloads yet — again, still talking albums here. But it’s only a matter of time. Whether streaming or iTunes-style downloading, digital sales will only increase as physical media slowly goes the way of the dinosaur.

But what about right now? We aren’t yet anywhere near a point where CDs are hard to come by. Lots of stuff is available via download but not quite everything, especially if we want lossless quality or if we focus on obscure catalog titles. CDs have the advantage of a thriving used market — which hasn’t yet been figured out for downloads. The usual tactic is to buy the CD, convert to lossless files via computer, and store the original away as a backup. But how to play those digital copies? Do you want a PC or Mac in your listening rig? For many people that’s the answer, either by preference or just due to lack of alternatives. Enough progress has been made in the category of audiophile playback software where this is a viable option. But for various reasons, some people seek an alternative.

Enter the Music Server. Or Streamer, or Media Bridge, or Renderer … or whatever we decide to call it. There’s disagreement, depending on who you ask, as to which term means what. By the classic (and maybe not quite technically accurate) definition, a music server is something which “serves” music stored on a hard drive of some type. I call it “classic” because you can search eBay for “music server” and find some ancient examples, like Escient and Crestron and the like. If custom integrators were happy with the term well over a decade ago, I see no reason to argue it now. So by my logic an iPod would qualify as a music server but a portable CD player would not. Nowadays, in our networked world, a server is often thought of as something which can “serve” music across a network connection, usually with a different device receiving it and playing it back. But I contend that a network is not a necessary component.

Anyway, your PC or Mac could be considered a music server if you’d like, but that’s what we’re trying to avoid here. Why? Multiple reasons actually. Mainly, I’d say it’s because computers tend to be noisy, power-hungry things, which really weren’t designed with audio in mind. If we work hard at it we can achieve good results with the right combination of hardware and software, but the fact remains — it’s still a general purpose computing device being shoehorned into a specific role. Some people will want better aesthetics, or more efficiency, or more specific connectivity, than a PC or Mac can easily achieve. Others may just want to avoid using a device that they spent all day using at work – which seems like a valid excuse to me. That’s where music servers (or whatever we choose to call them) come into play. The idea is that we can have a device built from the ground up with audio performance in mind, which takes less power, and has less extraneous features, and looks better in an audio rack, than a normal mass market computer.

This leads me to the product under review – the Auraliti PK90. For their part, Auraliti wisely sidesteps the semantic controversy by calling their device a “File Player”. Hmmmm …. I like it. It’s unambiguous and doesn’t have baggage like “server” does. But I’ll probably still use Music Server as a catch-all term because that’s what I’m used to. Apologies if that offends your technical sensibilities.

As a company, Auraliti is not a massive audiophile empire. In fact from what I can tell it’s just two guys for the most part. Ray Burnham is the face of the company, acting as the marketing department, customer service, tech support, etc. I don’t know his full story but I get the impression he probably had (or still has?) a day job in the IT realm. The second person, sort of a “behind the scenes” partner, is Demian Martin. If the name rings a bell, it’s because Demian has been at this for ages. He founded Spectral Audio, and has designed for such esteemed audio firms as Constellation Audio, Rockport Technologies, and NuForce (among others). So there’s definitely some HiFi street cred in action here. Despite that pedigree, Auraliti gear is not at all unattainable in terms of price. The PK90 under review here is just $949, which could be called downright cheap considering the landscape.

Unlike many of its competitors, the PK90 is a complete stand-alone system. Although it can now stream music from a NAS (Network Attached Storage), it wasn’t always so — the initial focus was on direct connection to external hard drives, and that’s still how I use mine most often. The disclaimer? Auraliti has just a single button for power on/off. There is no method for accessing content. As such, it requires a network connection for control purposes. Options are plentiful — use the mPad app on an iPad, or mPod on an iPhone, or any number of MPD controller apps for Android, or even through a simple web-based controller from another computer (but where’s the fun in that?). Network connectivity is required and is achieved via Ethernet only – there’s no provision here for WiFi. Later, I’ll discuss strategies for making Ethernet work where you don’t have a prewired network.

The Hardware

I’ve been asked quite a few times on various forums – what exactly is the PK90? Apparently some people find it difficult to comprehend. I’ll admit the Auraliti website is not the greatest, but the device itself is fairly easy to “get”. It’s basically a purpose-built computer running a special version of Linux, and dedicated solely to audio playback. For the true geeks out there — Auraliti started with Voyage Linux back in the day, before Voyage MPD existed. They have forked enough to where their version is similar to Voyage MPD but not interchangeable. Anyway, the PK90 has relatively low specs in comparison to a general purpose PC or Mac. But remember, it’s optimized for audio playback only. So it’s not fighting for resources like a normal system is. No special playback or tweaks required — it’s all done for us from the start. The operating system lives on a small read-only drive and as such can not be bungled by the end-user. Believe me, I tried …. Also worth noting is the complete lack of any noise. The PK90 used passive heatsinks so there are no moving parts involved and therefore zero noise.

Physically, the PK90 is a very compact unit measuring 7.5″ x 7.5″ by 2.3″. Auraliti was using a fairly basic enclosure but recently switched to something a little more heavy-duty. Higher end aspirations are more readily achieved with this new case – it looks like a shrunken and simplified Ayon Audio CD player, same rounded corners and everything. The front panel is deliberately sparse with just a single power button and a USB input (for easy access). Rear panel is where the action is: 3 more USB ports for attaching storage, the network plug for Ethernet, and then some vestigial computer ports (VGA, DVI, etc) that we don’t need to worry about. Last but definitely not least is the SOtM tX-USB which is used to provide an ideal USB connection to your DAC. From the SOtM literature:

The SOtM tX-USB is an audiophile PCI to USB audio card like no other. This audio card has a unique design incorporating a power line noise filter. It then has individual ultra low noise regulators to power the USB devices attached, the on board ultra low jitter clock and the on board PCI host controller. You can also use the audio card’s power connector (4 pin Molex) to supply it with your own linear or battery power supply for an additional boost in performance. The audio card also has a convenient switch to turn off the power on the USB cable all together. It simply does not get any better than this!

This card retailed for $339 until it was just recently discontinued to make way for the PCI Express version. This USB card is an essential component in delivering clean power to your USB DAC of choice, which turns out to be more complicated than many people may realize. Chris Connaker at Computer Audiophile has been recommending these SOtM cards for years and I can absolutely see why. With most new DACs having a large focus on their asynchronous USB input, it makes sense to go this route — it should theoretically give us better jitter performance compared to “legacy” SPDIF connections. If you really wanted to avoid USB, there’s the PK100 which sports a BNC output. Personally I’d recommend the USB version every time, based on where I see DAC makers focusing their efforts.

Another aspect of the device which I need to touch on is the power supply. Now, in stock form, we get a wall wart. At $949 (including shipping in the USA) that’s not surprising. Add up the cost of a small form factor PC, plus the nice enclosure and the $300+ SOtM USB card, and it’s pretty clear that Auraliti is not making a killing on each unit. But since we aren’t spending a bundle on the device itself, there may be some room left in the budget for a dedicated power supply. Remember, that SOtM USB card has the additional Molex connector, so it can take full advantage of superior power whenever possible. And now Auraliti has their own power supply, an all-new design by Demian Martin. The PK power supply (my name, not theirs) goes for $399. So the full package price for the PK90 plus linear power supply, including shipping in the USA, is $1348. Which is still peanuts compared to a lot of the alternatives out there. Buyers outside the USA will pay somewhere around $50 for shipping.

Speaking of alternatives: let’s talk for a second about what the Auraliti won’t do. This thing doesn’t stream internet radio. It won’t do Spotify. It has no optical drive so it won’t rip your discs for you. There’s no display on front for showing cover art, and no buttons for even the most basic transport controls. There’s no built in WiFi so you’ll absolutely need a hard-wired connection. Are you starting to get the picture here? The PK90 is a slimmed down, just-the-basics design that focuses strictly on sound quality and bang for the buck. If you wanted some of those features – and I wouldn’t fault you if you did – you’d need to look elsewhere. Options are plentiful: Cambridge Audio has their Stream Magic 6, Olive Media has several devices, Sony has some new DSD capable gear, Weiss has their high-end MAN301, SOtM has some options of their own, Aurender has a couple nice ones … not to mention more basic streamers from NAD, Pioneer, Marantz, Denon, et al. A quick glance at recent CES coverage shows this is a booming segment, so Auraliti was ahead of the game by launching their products a few years back. Another early entry was Bryston with their BDP-1 ($2,195). Guess who had a hand in that design? Yep, Auraliti. That device is based on Auraliti’s upscale L1000 model about which I know very little, but the point here is that Auraliti has been doing this longer than most. If you don’t want or need the extra features I mentioned above, the Auraliti is a simple and very effective way to go.

Just so I don’t get you down by listing all the features it doesn’t have, let’s talk about what the PK90 can do: Auraliti lists it as supporting FLAC, WAV, and AIFF lossless files, but I know from experience it also does MP3 and AAC lossy files (sacrilege!) as well as some less common stuff like OGG. It handles gapless playback of everything from 16-bit/44.1kHz (CD quality) files through 24-bit/384kHz hi-res tracks. It also supports the oh-so-popular DSD format in both DSD64 and DSD128 varieties, saved in either the DSF and DFF file format (DSD support, along with max PCM sample rate, are determined by your DAC capabilities). It can stream from a network using either SMB or NFS sharing, which means pretty much any NAS or any computer running Windows or OSX will do the trick once properly configured (which shouldn’t be too difficult). The device can accommodate up to four local storage devices which can be anything from solid state USB sticks to external hard drives. Hard drives can be the portable variety (powered by USB) or else the stand-alone type with their own power adapters. The SOtM output card even has a switch to disable power over USB altogether – this requires a DAC which doesn’t draw power from the USB line, and seems more relevant when using the card in a standard PC with dirty power. But it’s still a nice feature to have “just in case”.

Odds and Ends

A few more areas I need to touch on. First, tagging. If you’ve been maintaining a digital library for a while, you’ll know all about the importance of properly tagging your music in a consistent manner. Gone are the days where a simple directory structure was all it took to organize a collection. With multiple terabytes of music to sift through, you really do need good tagging for artist and album info. If all your music comes from CDs you ripped personally, then you’re probably in a good position. I’m not sure that applies to most people though. I’ve ripped all my CDs, purchased tracks from over a dozen websites, downloaded free tracks straight from artist websites and other free (legal) repositories, gotten USB drives at events and concerts which contained music …. The list goes on.

There are many ways to obtain music and not all of them will contain proper metadata, much less consistent metadata. I use, and highly recommend, a little program called Bliss for automatically cleaning up my collection. It sifts through many terabytes of music, correctly tagging and adding art as it goes. Out of thousands of albums, Bliss has been staggeringly accurate, with only the rarest of rare stuff needing manual help. I can’t fault Bliss for not knowing about an unsigned local band who handed me a demo CD. And I don’t believe it knows what to do with my SACD rips from a PS3. But then again .ISO is not traditionally a music format so I understand that limitation. Other than that I’ve spent precious little time on the whole thing, and gotten very satisfying results. I can’t stress enough how important proper tagging is to making the PK90 (or similar devices) a great experience, and I can’t overstate the capabilities of the Bliss software if you don’t want to spend a lot of time tweaking things yourself.

The other aspect I have to mention is the network connection. If your house is prewired with Ethernet, consider yourself lucky. If you have the access and knowledge to run Ethernet yourself, please do so. If not, you’ll have to find some other method, and I have a few to recommend.

First is “power line networking” which basically transmits data over your existing home electrical wiring. It works well on a case by case basis, and is both easy to setup and inexpensive. Definitely worth a try. The downside? It isn’t always the fastest, which isn’t a factor if you just need the network for iPad control, but may be an issue for streaming hi-res content from a NAS. Also, it doesn’t work with power conditioners, which makes it less friendly with audiophile systems.

Next is a lesser known but in my opinion more effective solution called MoCA networking. Think Powerline, but this time using the existing coaxial cable in your home. Again, this is dependent on your particular home – what works for one house may not work for the next, depending on how your cable/satellite installer provisioned the lines. When it does work, it’s simple and usually more effective than Powerline in terms of speed. This is what I currently use for streaming demanding content such as HD video and DSD audio, and it never lets me down.

Lastly, another option I’ve used with good results, is to simply use an old router as a wireless bridge. True geeks like me tend to have a router or three laying around, and many routers have the bridge option built-in. If not, they may be compatible with the DD-WRT firmware which enables it. A wireless bridge does just what the name implies, resulting in a hard-wired connection without actually running cable from room to room. Speeds are obviously dependent on your existing WiFi network but this can be an easy solution if you’re comfortable messing with router settings.

In Use

It took me a while to get a handle on operating the PK90 in my system. I couldn’t exactly put my finger on why, but eventually I figured it out: I had conditioned myself to expect a direct connection to my source, sitting right next to my other gear. I play, or skip tracks, or whatever, by pressing buttons on a front panel. As a headphone user this was doubly strong in my case, since I rarely get far enough away from the gear to require a remote. Sitting in my listening chair, headphones on head, equipment rack to my right side: it just felt wrong to browse tracks and control playback from a tablet device that I held in my hands. This “disconnect” sounds silly when I describe it now, but it was a real hurdle for me at the time. Eventually I got over it but it took a while. After trying various control methods, I prefer using mPad on my iPad – for me it has a superior user experience compared to the various Android apps. But it’s nice to have options.

The other thing one needs to get used to is the massive library available. Maybe it’s no big deal for people accustomed to computer audio. Folks who are used to browsing a CD or LP collection may find this intimidating. An analogy – remember video stores? Blockbuster and the like? The analogy works even better if we use a smaller, local video store. The first time you walk in there, it’s overwhelming, but after repeat visits you start to have a good handle on the categories and catalog titles. You start to have an idea about what you’d like to grab, or what you might be in the mood for, even before you walk in the door. And you generally know where to go in order to find it. In my analogy, this represents a physical collection of music – even a large one. Now contrast that with the Netflix interface where you may sometimes find yourself hopelessly buried in choices. Yes, there’s some helpful categorization, and even a personalized list, but it can all become a bit overwhelming at times. When faced with a massive amount of options, my brain seems to shut down to some degree. The broader my options, the more difficult time I have choosing. I was a bit relieved when I found out I wasn’t the only one to have this problem. Apparently that’s just how most brains work. Is it insurmountable? Of course not. But it does require some experience with the new system to come to grips with the situation. Even though I’ve been using an iPod packed with music for years, and playing music on my desktop system from a fully loaded hard drive, somehow that didn’t translate to my big setup. By now I’m used to it and enjoy it quite a bit, though I still keep a CD transport handy for occasional use.

The Sound

Now, after reading all that, I bet you want me to hurry up and get to the point. I wish I could easily define the sound signature of the PK90 … but it’s not that simple. At times I’ve owned this or that transport which consistently imparts the same sonic signature on every DAC I pair it with. But that’s the exception, not the rule. Most times it really depends on the DAC itself. A transport which I consider “good” will sound “good” with most DACs, allowing each to excel in its own way. A “poor” transport will hold back anything it feeds, some DACs more than others depending on jitter rejection capabilities among other factors.

So how does the Auraliti PK90 do as a transport? Well, compared to most CD transports I’ve used, there’s no competition — the PK90 blows them away. I’m not talking cheap DVD players repurposed for transport duty either. I’m talking quality players from Marantz, Lexicon, Audio Research, and Classe. In general terms, I’d say the PK90 is at least on par with the best dedicated transports I’ve owned from, from the likes of C.E.C. and Levinson. Though with many modern DACs I actually get better performance with the Auraliti. Universal improvements tend to follow the same path: blacker background, more startling dynamics, more weighty low-frequency extension, and — this part is probably the biggest improvement — more expansive soundstage and accurate imaging. All those little “high-end” touches that people spend an awful lot of money chasing? Yep, the Auraliti helps you get there and doesn’t cost a fortune in the process.

Since this is just my own personal gear that I purchased more than a year ago, and not just some review demo on loan for a few months, I’ve had plenty of time to play with various DAC combinations. Most of the pairings I’ve tried show a moderate to substantial boost in performance when switching to the PK90. But there were a few exceptions.

I used budget champions like the Parasound Zdac and the AMI DDH-1, and in both cases thought the PK90 was more resolving than just using a MacBook over USB. I used more substantial devices in the $1,000 to $2,000 range such as the Anedio D2, Violectric V800, and NuForce DAC-100. Again, the PK90 delivered consistently better results as opposed to USB from the MacBook, as well as compared to reasonably nice disc-based transports. Finally I moved up to some higher-end DACs such as the Esoteric D-07x, E.A.R. Acute, and a North Star Design Supremo. This is where the comparison gets interesting because here especially, I sense a distinct advantage from the PK90 as compared to the rather expensive C.E.C. transport I have on hand. You don’t know what you may be missing at first, and the C.E.C. does produce fantastic sound. But when comparing them directly I’d say the PK90 brings out more of that “you are there”, spine-tingling realism. The Esoteric D-07x was interesting in that I could emphasize or minimize the differences depending on which settings I used for reclocking, digital filter, and PCM to DSD upsampling. There’s a lot to play with on that particular DAC and when I maximized it for what I thought worked best with USB, the divide between USB and disc-based transport grew even larger.

Not every DAC showed such a large difference though. There were a few which coasted by without much benefit. The Bryston BDA-1, for example, did not seem to show any difference at all between the Auraliti and the MacBook. It has an older adaptive-mode USB solution which probably sets the tone for maximum performance anyway. I suspect the newer BDA-2 would pay much larger dividends with its upgraded asynchronous USB section.

I also ran into a few anomalies where the DAC didn’t play well with the PK90. My reference DAC, the Resonessence Labs Invicta, had an odd situation where it played 24-bit/96kHz material perfectly, yet anything else produced obvious static or else flat-out refused to play. There must be some beef between Auraliti’s Linux build and the relatively uncommon Cypress Semiconductor USB solution in the Invicta. A software update from Resonessence Labs in late 2013 seems to have fixed the issue but I haven’t had a chance to thoroughly confirm.

Another mismatch was the overachieving BMC PureDAC, which simply refused to play ball with the PK90. I believe they use the XMOS chipset for USB which has always proven reliable with Linux, so I’m at a loss as to why the pair won’t cooperate.

Which brings me to another option — if one wanted to exploit the benefits of the PK90 but desired/required an SPDIF connection, the combination of PK90 with Audiophilleo USB to SPDIF convertor is highly recommended. My setup uses the Audiophilleo 1 with PurePower battery option, and the result is breathtaking. In fact with some sources (Meitner MA-1 for example, which lacks galvanic isolation on the USB input) this would almost be mandatory. I imagine one could get away with the Audiophilleo 2 for $579 and get pretty far along — with the PK90 providing clean power, the PurePower option is less of a necessity than it is when used with a laptop (though it still makes a difference). The total price in that — PK90, Audiophilleo 2, and Auraliti linear power supply — is under $2,000 … a drop in the bucket when considering the $7,000 asking price of the Meitner MA-1. This gives the benefits of ultra-low jitter asynchronous USB connectivity, while bypassing the weak link of this particular USB design. It’s win-win.

Speaking of power, here’s my quick take on the upgraded linear power supply option: do it! The stock wall-wart included by Auraliti is not terrible. The system doesn’t turn to mush, and performance doesn’t fall off a cliff. When using a somewhat modest DAC I’d say it doesn’t really matter all that much. However … when using a highly resolving DAC, the linear power supply is clearly beneficial. Considering the price, it seems like a no-brainer to me. Turn a really good transport into a world-class transport for an extra $400? Yes, please.

At the End of the Day

Notice how much of this article focuses on setup and user experience compared to sound quality. Those aspects are huge. Yes, the PK90 happens to sound extremely good with most DACs, but that wouldn’t matter if the user experience wasn’t there. For me, the PK90 has turned out to be everything I hoped it would be, and then some.
The device is so simple and effective as to beg the question: why hasn’t anyone else done this already? The answer is that people actually have done this on their own, but commercial offerings have tended to go in other directions. I’m just now spotting other brands which emphasize a quality USB output, while Auraliti has been at it for several years by now. The head start pays off in terms of product maturity – frankly, a lack of marketing is really all I see holding them back from becoming far more popular.

If your DAC is a modern design which emphasizes the USB connection, I see nothing else on the market coming close to the Auraliti PK90 for sheer value. You can build it yourself, but don’t expect to save massive amounts of money in the process, assuming you want to do it right. Does it get any better than this? Maybe, maybe not. I’ve heard others, similar in nature but way more expensive (such as Music Vault or Antipodes), and I have yet to find anything that sounds clearly superior. Slightly different? Yes. Better? Not really.

I admit I may have just painted myself into a corner here — can I ever cover another music server costing more than this and find any value in it? Is this my one and only review for a device of this nature? We’ll see. But that’s my problem, not yours. If you are in the market for such a device, and are willing to work inside the scope of requirements for networking and library management, the Auraliti PK90 should be at the absolute tippy-top of your list.