COMPARISON OF 5 HIGH-END MUSIC SERVERS - Aurender N10, CAD CAT server, TotalDac d1-Server, Auralic Aries and Audiophile Vortex Box In the typical digital headphone chain, the chain generally begins with the digital source followed by the DAC, pre-amplifier, amplifier and finally the headphone. It has long been my contention that in this chain, the headphone is the most important piece. In my recent article for Inner Fidelity as a participant of Tyll Hertsens’ Big Sound 2015 (http://www.innerfidelity.com/content/big-sound-2015-participant-report-roy-romaz#B1XGewqDPFt3TyjO.97), one of my concluding statements was “Find the headphone that you love first, everything else comes second.” From here, logic would suggest that the headphone amplifier would be the second most important piece of the chain and then you simply work your way backwards leaving the digital source as the least significant piece. After all, bits are bits, aren't they? Recent revelations have now caused me to reconsider my position. For the beginner head-fier looking to put together his or her first headphone system, this recommendation of “headphone first” remains the best words of wisdom I can impart. For those of us further along in our head-fi journey, however, I now believe the opposite may be true. For many of us who have been at this hobby for awhile, I find it interesting that most that I speak with own or have owned at least 2 headphones already and seem to always be in search of the next one because for some reason, their collection is always somehow inadequate or no longer engaging. Before long, many of us have spent 3- and even 4-figures amassing more and more headphones as if the portal to audio nirvana lies within that next headphone. Moreover, many of us subject our headphones to tweaks and mods and while these things have their place, many, including myself, have failed to consider that perhaps the headphone is not the problem nor is the headphone amp or DAC. Perhaps we’ve been channeling our resources disproportionately to all the wrong areas and just maybe those bits aren’t just bits. Some of you will argue my claim but as one of my good friends and fellow head-fier is so keen to say, “if it’s not in the source, then it’s not in the headphone.” Those of you coming from a vinyl background probably have a better sense of this already. If you think about it, an excellent headphone improves nothing before it but an excellent source improves everything after it and in a digital system, most DACs, amplifiers and headphones are resolving enough today to reveal as good a source as you can place before them suggesting that the source is often the limiting factor. Having built several dozen computers dating back to the days of DOS and as the head of IT in my own business, I’ve taken a crack at building several music servers for myself and others. While I have not gone as far as building a fully tricked out dual box PC, I have benefited like many others from the guidelines posted by Chris Connaker in Computer Audiophile. For years, Chris has championed the idea that a DIY CAPS server could provide a superior listening experience and so for some time, I had assumed that some of the CAPS machines I had built were as good as it got. This belief was supported by my experience with other purpose-built devices including a modified Mac Mini, Moon MiND, W4S Music Server MS-2, Aurender X100, Auralic Aries and an Audiophile VortexBox as these devices at their best were only on par with what I had built. In other words, there was not much that separated these devices. Well, on April 1, 2014, Chris Connaker, the man responsible for the CAPS server as we know it, proclaimed in his review of the Aurender W20 that the W20 sounded better than any server he had ever used. In his words, “the Aurender W20 makes CAPS servers look like children’s toys with inferior sound” (http://www.computeraudiophile.com/content/573-aurender-w20-review/). On July 19, 2015, DMelby wrote a nice review of the Aurender N10 on Computer Audiophile that essentially said the same thing. In his words, "I found, simply, that the N10 sounds better, by every measure, than my CAPS" (http://www.computeraudiophile.com/f10-music-servers/aurender-n10-review-25192/). By this point, it had become clear there was something to both the Aurender W20 and N10 that were superior to any of the digital sources I had thus far listened to and I knew I had to investigate the N10/W20 further. After scouring other forums and speaking with other head-fiers who have similar tastes, two other music servers piqued my interest, the TotalDac d1-Server and the CAD CAT server. As I evaluate these three servers, I will disclose that at the present time, I do not own these units or at least I have the option of returning them. I do still presently own an Auralic Aries and Audiophile Vortex Box and so I have decided to include them for comparison. While all reviewers hope to be as unbiased as possible, it has been my observation that most are partial to something they already paid good money for and indeed this is true for me. The burden of proof is always on the challenger and less on the incumbent. As for equipment used to evaluate these digital sources, here is my equipment chain: digital source -> TotalDac USB cable -> USB Regen with linear PSU -> TotalDac d1-monobloc DAC -> HE-1000 headphone with Silver Spore4 cable by DHC. To better assess soundstage and imaging, listening was also performed through my 2-channel system comprised of my Omega Super 3i monitors powered by a Bantam Gold amplifier. You will notice that a headphone amplifier is not mentioned in my chain and that is because the TotalDac d1-monobloc DAC is capable of driving headphones directly through its balanced XLR outputs and I found the transparency of this direct connection superior to that of my Eddie Current Balancing Act with PX-4 tubes. For evaluating any digital front end, I can think of no better way than this direction connection. I’ve had at least a couple of weeks with each digital source to the extent that I feel comfortable with the sonic character of each. Files used for evaluation include a mix of DSD and PCM as uncompressed FLAC/WAV/AIFF and Tidal streaming. Ok, so after perhaps the longest introduction in history, here is my take on these digital sources: Audiophile Vortex Box by Small Green Computer with 1 TB SSD, SOtM USB card and HD Plex linear PSU ($1,954) This is a well-implemented device that works as advertised and has proven to be reliable and trouble-free over the 18 months that I have owned it. It runs silently, consumes barely 20 watts and runs cool to the touch so I run it 24/7. In addition to being capable of playing all formats up to dual DSD as well as Tidal and Spotify, it is also an excellent CD-ripping device. When not used as a music server, it also very competently fills in as a high-level NAS and so this unit also performed NAS duties for the other units in this review. It runs Linux with a minimal number of process running and so it has a very quiet software footprint. As far as SQ, it does everything well and plays everything without fault. Presentation is balanced and compared to the other devices I have owned in the past including a customized Mac Mini and several Windows boxes I have built, it was at least as good (often better) and proved to be more reliable and convenient and so those other servers were either sold or repurposed. Auralic Aries with linear PSU ($1,599) I found a used one for an excellent price earlier this year and so I bought this unit based on so many excellent reviews. This is a very good streamer that is also based on Linux and relies on a NAS or USB hard drive to play music that you own although streaming from NAS has easily been the superior experience for me. I have tried streaming via wi-fi and ethernet and my experience with wi-fi was initially superior although this difference went away when I moved my router to my rack and upgraded my Blue Jeans CAT 6 cable to an audiophile CAT 6 cable made by SOtM. It took me a long time to buy into the benefits of audiophile USB cables and it took even longer to believe there were differences among CAT 6 cables but the proof is in the listening and with blind testing, I was able to pick out the SOtM cable consistently because with the SOtM cable, volume increased by at least a decibel and the soundstage appeared slightly more material. I would rate the sound quality of the Auralic Aries as equivalent to my Audiophile Vortex Box meaning it does everything well. In isolation, you don’t get the sense you are missing anything although I have to say that the music I heard never resulted in the same engagement I have heard with the vinyl systems that certain friends have. Where the Aries surpasses my Vortex Box is in its software interface. It’s Lightning DS app for the iPad is beautifully implemented, intuitive and reliable. I cannot overstate the importance of the software interface for me. From the standpoint of overall user experience, the Aries is superior because of its software interface. Aurender N10 ($7,999) The Aurender N10 has Linux underpinnings as well. From what I have been able to gather, aside from the two 2 TB Western Digital Green hard drives, Samsung SSD and RAM, the internals of the N10 including the motherboard is an Aurender design. I had also targeted the W20 although with an MSRP of $16,800, you’re forced to wonder if that player is twice as good. I spent a day with a W20 during my time with Tyll Hertsens at Big Sound 2015 and the W20 played superbly. My initial comments after hearing everything Tyll had on hand was that everything sounded really good. There wasn’t a lemon in the bunch and differences came down more to personal preference than night and day superiority among the various headphones and amplifiers. Initially, I attributed this to the cumulative impact of excellent AC power and TOTL cables but in hindsight, I wonder if the W20 had more to do with that experience. After speaking with my Aurender dealer who had both units on hand and had good personal experience with each, his opinion was that unless you can take advantage of the dual AES/EBU output and external clock option of the W20, the N10 and W20 are sonically equivalent and so we mutually decided he would send me his N10 evaluation unit which was fortunately already well broken in. Within the first 30 seconds of listening to the N10 in my own system, I knew exactly what Chris Connaker and DMelby were saying. It didn’t take a few hours and I didn’t need to run through a long list of music to understand that what I was hearing was superior in EVERY way. I went back to my Aries and Vortex Box and this confirmed what I was hearing. There was no need to even consider blind testing because the differences were not subtle. It was like watching Blu-ray vs DVD or listening to FM vs AM radio. I decided to downgrade my TotalDac d1-monobloc DAC into a d1-dual and then proceeded to substitute it with my Bricasti M1 and with each DAC, the differences were consistent and real. The music I was hearing was just more “material” and felt more dynamic and full-bodied. The timbre and decay of every difficult instrument to reproduce — pianos, violins, cymbals, etc — were excellent. Detail was exquisite, especially the layering of detail. The soundstage was expansive and the sense of space and air was intoxicating. Whether it was a solo vocal in an intimate venue or a grand orchestral performance, the level of engagement to what I was hearing had been multiplied several fold. TotalDac d1-Server ($4,925) Compared to the Aurender N10 and CAD CAT server, this is the value proposition of the three. If you are targeting the TotalDac d1-monobloc DAC, since it already incorporates a relocker, the Server option actually adds only another $1,000 and so this option for that DAC is a no brainer. When combined with any TotalDac DAC, there is an obvious synergy present as one was made for the other but the d1-Server plays superbly with even my Bricasti M1. Like the Aurender N10, this server plays at another level altogether against my VortexBox and Aries and again the differences are quite stark. Like the N10, the sound you get is powerful, dynamic and full bodied. It embodies the TotalDac “house sound” in terms of vivid and rich tone with a bloom superior to the N10. The N10 presents a larger soundstage and details are a bit better finessed; however, it is a matter of splitting hairs between these two sources. In direct comparison, these two units are sonically more similar than different meaning that both are superb. The overall user experience with the N10 is better, however. While both are Linux-based, the TotalDac d1-Server is much more like my Vortex Box than the N10. It utilizes MPD on an iPad which I find to be second rate software compared to Aurender’s Conductor app. While SQ from MPD is as good as Aurender’s Conductor, usability and reliability is better with Conductor. MPD is buggy and clunky in comparison and you cannot stream Tidal from MPD, you have to step down to another application called iPeng which unfortunately also results in a step down in SQ. All of these complaints instantly go away if somehow ROON with its superior library skinning abilities and excellent Tidal integration can be ported to and optimized for the TotalDac d1-Server although for now, according to Vincent Brient, TotalDac’s creator, there are no plans. CAD CAT server with 1TB SSD internal storage ($7,277) This is a purpose-built PC that runs Windows 8.1 and on face value, I would normally have no interest in such a machine. Having plenty of experience building my own PCs, I was convinced I had already experienced the pinnacle of Windows-based servers and that they did not compete on the same plane as the N10 or TotalDac d1-Server or even Linux-based CAPs devices. It was, in fact, with some reluctance that I agreed to evaluate this unit especially given its asking price but after detailed discussions with @isquirrel who owns this server and after even more detailed discussions with Scott Berry, the creator of the CAT, I decided to give it a go, especially as Scott offers a 30 day money back guarantee. It turns out this CAT is easily more than the sum of its parts and with this machine, you may actually get more of what you pay for. Scott was quick to point out that the parts used for his CAT are far from off the shelf. He spent nearly 4 years in its design and development. What Scott has found to be one of the biggest issues in digital audio is high frequency noise that results in digital harshness and so he has obsessed about finding ways to eliminate or minimize it using a variety of methods and technologies that he did not feel he could share with me. He did say that the motherboard is heavily modified and incorporates a custom BIOS that has taken years to refine. The motherboard uses 2 oscillators/clocks that receive a highly filtered DC voltage from an outboard linear PSU. There are no motherboard switch mode regulators between the oscillators and external power supply. There is also additional filtering applied as close as physically possible to both oscillators. His USB ports are of his own specification and are fed by a dedicated rail from his external linear PSU. The OS is installed onto a small dedicated SSD with data stored on separate SSDs that have been custom manufactured to his specifications and optimized for music playback. His SSDs cannot be user installed in the same way that his team installs them as they are individually encased, shielded and carefully mounted to guard against resonances. All of his cabling, both data and power, are of his own design after considerable experimentation with different metallurgy and his CAT is handwired to keep lengths to a minimum. The unused ports on his CAT have been deactivated. When run headless, even the integrated video card is deactivated. While he uses a low power quad-core Intel CPU, it has intentionally been dethrottled to run at a specific frequency that he found optimum and just enough to drive necessary processes. As I used FireFox to download my DAC’s ASIO driver, I noticed how sluggish it was and so without question, this CPU has been detuned. The proof of this is the CAT barely consumes 20 watts and runs cool to the touch at all times. Scott spent nearly 3 years optimizing Windows 8 for audio playback and much of these optimizations are highlighted in the thread he started on Computer Audiophile (http://www.computeraudiophile.com/f11-software/windows-8-audio-optimization-script-16353/). Scott is quick to point out, however, that not all of his optimizations are revealed on this thread and have been reserved for his servers. To keep his OS running reliably and optimally, it has been locked down. No firewall is active and antivirus software and Windows updates are strongly discouraged as they are not felt to be necessary for a music server. In my time with the CAT, I have run it 24/7 and I can attest it has run reliably. Scott further defended his use of Windows 8.1 given its robust networking capabilities and very broad compatibility including the option of running ROON headless. Using an iPad, Android tablet, PC or MAC, I can remotely run ROON on the CAT and the experience has indeed been excellent and superior even to Aurender's Conductor or Auralic's Lightning DS. I have found no better way to organize and play my collection of over 1,000 CDs as well as discover new music as ROON’s Tidal interface is better than even Tidal’s own interface. What about SQ? I saved this for last. As good as the TotalDac d1-Server and Aurender N10 are, the CAT is better. Not night and day better but better in important ways. The presentation is both smooth and effortless yet incisive at the same time. It embodies the tonal richness of the TotalDac d1-Server but outdoes the TotalDac in terms of tonal clarity. There is a more vivid sense of presence on vocals. It matches the soundstage of the N10 and improves on the N10s ability to render delicate details and subtle nuances. The bass on the CAT is fuller, tighter and better defined. The treble is well extended, maybe even a little more airy than the N10 but both excel here. It also lacks the slight digital edge present in the treble of the N10 that was not obvious except under direct comparison. Tracks that I previously considered bright now seem more tolerable. My gut tells me that the CAT’s well-designed outboard linear PSU with its four separate rails has something to do with this. Having read the recent review by @dan.gheorghe on how a more robustly built power supply transformed his already excellent MSB Analog DAC, without question, the quality of the power supply matters (http://headmania.org/2015/11/01/volent-audio-custom-lps-for-msb-analog-dac/). An even more robust linear PSU is being designed for the CAT by Paul Hynes and it is scary to think how much better this CAT can sound because as of now, it is the best I have heard. Something else I never considered before, the better the source, the more illuminated everything else sounds after it and the better components seem to receive the greatest illumination. While the Bricasti M1 and TotalDac d1-dual each benefit greatly from these fine sources, the largest beneficiary is the d1-monobloc. It’s as if this was where the biggest choke hold was occurring and set free from confinement of lesser sources, the monoblocs were showing how much higher it could scale compared to the other two. Similarly, with the HE-1000 and a highly resolving cable like the DHC Silver Spore4, I have never heard this headphone sound better. I used to believe that gear like a $25,000 DAC was overkill for headphones because headphones were incapable of scaling to equipment like this and in truth, one of the reasons I decided to take part in this exercise was to see just how high the ceiling is. Well, I have now found how high that ceiling is and it is as high as your source will allow because I now firmly believe for most high-end digital headphone systems, the digital source is the limiting factor. As for the value proposition of this kind of setup, you will have to ponder this for yourselves. For a 2-channel setup, somehow, this is all reasonable but for headphones, many will suggest this is insanity although as many of you can attest, this audiophile hobby of ours is not a sane one. As to what I will be buying for myself, because negotiations are ongoing, I will keep that private. What I will say in closing is this, given the choice of a Mac Mini, TotalDac d1-monobloc and HE-1000 versus an alternate setup consisting of a CAD CAT, Schiit Gungnir Multibit and Sennheiser HD 600, I would choose the latter.