Another special






List Price: $780


Review by

Dr. John Richardson

Photography by Leonie Backhaus

            I can tell almost immediately if a product I receive for review is going to be easy or difficult to evaluate.  The easy ones are those components that just sort of glide effortlessly into my system and do their jobs in a pleasant manner without calling too much attention to themselves.  And when I say “calling attention to themselves,” I don’t necessarily mean it in a good way.


           The new X-DAC ($780 USD) from Rein Audio in Germany entered my home and announced itself as just such a component.  Maybe it’s a German thing.  My family recently acquired a high school exchange student named Leonie from Germany.  From day one, she fit right into the family, providing us with lots of pleasure and causing nary a bump in the road.  Likewise, the X-DAC joined my main audio system, made quick friends with the other components (and my computer), and never looked back.  Like Leonie when the time comes, I’ll greatly miss it when it has to go home.  More about that later, though.


           First off, who are Rein Audio?  I’m assuming that this company is probably as foreign to you as it was to me, especially since it has only been in existence for about a year.  So far, Rein Audio has specialized in the manufacture of high-end audio cables, an amplifier, and the X-DAC.  One thing I’ll  warn you about right now is their website.  From the point of view of this English reader, it’s painful at times to peruse. For example, interconnects are sometimes referred to as “cable rods.”   Even so, I get the gist, and it seems that things have been improving since I first looked at it a couple of months ago.  Another potential issue is that Rein has yet to develop a distribution base in the U.S.  As of now, the only way for folks here in the states to purchase their components and cables is on-line through their website.  This could be problematic if a customer needs to send something back for repair, for example.  Also, I’ll be up-front in stating that presently the X-DAC only runs on European 220 V mains.  This means that North American customers would need to invest in a step-down transformer to use the DAC.  Down the road, I’d love to see Rein Audio provide back-panel switches on their electronics to allow the user to choose between 110 V and 220 V mains, if not offer a dedicated 110 V version (I think this is in the works).


           I received the X-DAC from another reviewer here in the U.S., so I took it to be fully broken in.  It came double-boxed, but the original shipping label showed that it had originally arrived here in the States from Hong Kong.  My assumption is that the DAC was designed in Germany but manufactured in the Far East.  Whatever the case, the unit was certainly hefty, attractive, and assembled with a degree of precision that would seem appropriate to something manufactured in Germany.  As the Sham-Wow guy used to say, they make good stuff there.


           A quick examination of the unit inside and out indicated that this was no novice effort, even though it is the young company’s first digital product.  In fact, the website states that the X-DAC is the brainchild of company designer Tomasz Wilczak, a man who has reportedly had over 10 years of design experience in the European audio industry.  The DAC’s circuitry and power supply are enclosed in a very nice heavy duty iron and aluminum case that exudes overkill, giving the whole unit an elegant, but slightly industrial look.  On the front panel are two large dull metallic knobs and two yellow-green LEDs.  The left knob serves as the on/off switch, and the right-hand knob is the digital input selector.  Options here are coaxial 1 and 2, optical, and USB.  On the backside, the rear panel sports two sets of outputs (balanced XLR and single-ended RCA) as well as the aforementioned digital inputs.  On my early production sample, the RCA jacks are chassis mounted, which I really like from a durability standpoint.  Photos of subsequent production units indicate a change to what appear to be board-mounted jacks that protrude through holes in the chassis, which I don’t favor as much.


           The early production unit I received did harbor one disappointment for me.  While the company website claims that the USB input will process 24 bit files at up to 96 kHz sampling rates, my unit only offered 44.1 and 48 kHz options.  A quick check with Jason Tornald, Rein Audio’s ever resourceful and helpful director of sales, revealed that the early units indeed only processed files up to 48 kHz in resolution.  That’s a bummer for me as many of the files I use for evaluation are of the 24 bit/96 kHz resolution variety.  This little roadblock ultimately didn’t turn out to be a huge issue, as I spent most of my time listening to the X-DAC via one of its coaxial inputs, which process digital files with sampling rates up to 192 kHz.  Speaking of USB, Rein Audio’s website indicates that a synchronous adaptive protocol is used for data transfer between the computer and DAC; this is not the so-called “asynchronous” option that is so in vogue today.  My advice here to prospective buyers is to not worry too much about it.  The key to real success is in the implementation of the chosen protocol.  For example, the Benchmark DAC1 USB that I owned some time ago also used an adaptive protocol, and I found it to be absolutely ironclad.  If the implementation is done properly, then the DAC should perform well via the USB input and will probably sound good.

           On the inside, I found a well-laid out and tightly packed circuit board boasting good quality parts.  To the front was the power supply circuit, punctuated by a sizable transformer unit.  Now I understand why the X-DAC is such a hefty little box.  The digital to analog converter chip employed is the Wolfson WM8740 running in tandem with the CS8416 receiver chip.  This combination, according to Rein Audio, yields a most analog presentation of the music, providing harmonic distortion closer to the Bel Canto curve.  I take this to mean that whatever distortion there is sounds more musical, like the second order harmonic stuff that is so forgiving with vacuum tubes.   On the analog output end, twin AD797 operational amplifiers are used in a balanced configuration to match the 117 dB range of the Wolfson DAC.  These were chosen for their especially low noise and harmonic distortion properties.  Special care was also taken in the design and implementation of the power supply units.  Overall, the circuitry seems to be well thought out and implemented with components chosen exclusively for sound quality.


         The system in which I evaluated the Rein Audio X-DAC was my usual: a Mac Mini computer running Pure Music sending the digital bits out to a Metric Halo ULN-2  Firewire to S/PDIF digital converter which in turn fed the coaxial input of the X-DAC.  From the X-DAC, the analog signal was passed off to my Wyetech Labs Coral linestage and on to Threshold SA 3.5e and ODL HT-2 amplifiers driving Shahinian Compass speakers and a Shahinian Double Eagle subwoofer, respectively.  The only variation to this setup was when I was using the USB input on the X-DAC, in which case I bypassed the Metric Halo ULN-2 altogether.



           Let’s get back to the sound of the Rein Audio X-DAC.  I’ll preface this section of the review by saying that I have been lately quite impressed with the sound quality one can get these days from a sub-$1000 DAC.  These are indeed good times in the world of digital audio, with the gap between analog and good digital rapidly closing.  It’s taken a long time though.  I recall as a high school student in the mid 1980s listening to a local radio station DJ bragging about cueing up the latest rock hits on the vaunted “laser disc player.”  Oh, if he had only known....


           Well, let’s just say that with the Rein Audio X-DAC, I keep on being impressed.  Reiterating my opening comments, I knew this was going to be an easy review as soon as I heard the smooth, yet detailed presentation of the X-DAC.  I always like to live with a  component for a few weeks before putting pencil to paper, just to see if my initial opinion will change.  Sometimes it does, and sometimes it doesn’t.  In this case, it didn’t.  In fact, I listened to the Rein Audio DAC every day for weeks without really thinking about it being in the system.  I sort of forgot it was there.  Nothing seemed out of place; the music just kept on coming, naturally and in a most enchanting way.  I think this observation rang true because the X-DAC sounded almost indistinguishable from my house DAC, the Metric Halo ULN-2.  The trait that these two units share is their ability to sound eminently musical by striking an almost perfect balance between a smooth, musical presentation and detail.  Nothing seems tipped up or exaggerated in the audio band, and there isn’t that sense of “in your face” detail that can sometimes lead to a cold or clinical presentation over the long term.  However, if the detail and resolution aren’t there, my ears yearn for it, so this is an important set of qualities to get right.


           I also enjoyed a certain harmonic richness from the X-DAC that gave un-amplified instruments and voices a “rightness” that some other DACs just don’t seem to get.  I like to use vibraphone recordings (typically in a jazz setting) for a number of reasons.  First, nothing beats this instrument for assessment of attack and decay.  Second, a well-played vibraphone has almost explosive harmonic overtones that can frankly sound awful if not reproduced properly.  Get it right, however, and the listener is in for a real aural treat.  While all of this is highly system dependent, much of the credit or blame rests on the DAC, as it is the source component (along with the computer and its accompanying playback software).  I can say that the Rein Audio DAC does real justice to the reproduction of the vibes.  Whether it’s Bobby Hutcherson, Gary Burton, or Terry Gibbs, I always enjoyed what I heard.  Oh, and how could I forget the likes of Milt Jackson and Lionel Hampton?  Don’t worry, I’ve heard them all with the X-DAC in my system, and all have left a smile on my face.  I suppose that maybe things could get even better, but probably not for much under a grand.


           Take, for instance, the lively and sometimes deep-throated vibes on Bobby Hutcherson’s “Un Poco Loco” (Columbia LP, archived to 24/96 digital).  Via the X-DAC, I heard a rich, vibrant and exciting performance, with plenty of life and attack on the vibraphone.  Never did the vibes become overbearing or overly “ringy” like I have heard on some systems; they simply sounded brilliant in a tonal color sense with lots of reverberation and proper decay.  The same sentiments were also true of the other instruments in the mix of this late ‘70s example of the art of jazz fusion, whether it was the technical intricacy of Peter

Erksine’s staccato drumming, or the pure beauty of John Abercrombie’s guitar.  Altogether, this is a wonderfully tight performance that I could thoroughly enjoy through the Rein Audio X-DAC.


Next on the docket was some good, old fashioned straight ahead jazz, performed by some of the big guys:  Oscar Peterson, Joe Pass, Harry Edison, and Eddie “Cleanhead” Vinson.  This performance, on the Pablo Label (Oscar Peterson + Harry Edison + Eddie “Cleanhead” Vinson, Pablo LP, archived to 24/96 digital) features some great playing recorded in top-notch sound.  Some people ridicule the Pablo Label as a haven for washed-up old jazz artists way past their prime, produced by that old geezer Norman Grantz as a retirement hobby.  Hey, if that’s your opinion, then good; you’ll leave more of this great vinyl for me at still-bargain prices.  As I see it, these are wonderful performances by some of the greatest artists of the “real” jazz era produced by one of the greats of the industry.  I’ve rarely heard a bad Pablo, and I can’t say that about many labels out there.  Back to the recording...  If this was recorded digitally, and it probably was, it doesn’t suffer in the least from a sonic perspective.  The sound is so clear and natural that you can almost reach out in space and touch the players. 

           Although there are some great standards here, all played pretty much to perfection, I tended to languish on that nice old ballad “Everything Happens to Me.”  The piece starts out with Joe Pass soloing on the guitar, and is later joined by Harry Edison’s trumpet in an achingly lovely duet.  Through the X-DAC, I could easily picture Pass’ fingers on the guitar strings, and I reveled in the immediacy of Edison’s trumpet playing, especially his finely controlled shifts in dynamics.  He enters slightly to the left and behind Pass in barely a whisper, but by the end of the piece nearly knocked me out of my chair, playing considerably more loudly, but still very much in a smooth ballad-like manner.  Great stuff, indeed.


           Even though I felt that the USB option was a bit hobbled on my sample of the X-DAC due to its limited resolution capabilities, I wanted to see how it stood up to the coaxial interface, especially with 44.1 and 48 kHz files.  I’m happy to report that the USB interface worked flawlessly, with no hiccups, dropouts, clicks, pops, or other nasties.  Its musical presentation was also superb, and I felt that within its resolution limits it gave up nothing to the coaxial S/PDIF input.  What I got was the unabashed, unadulterated flavor of the Rein Audio X-DAC itself:  a smooth, highly detailed, harmonically rich presentation.    Disc after disc, file after file, I really couldn’t find anything negative to call out on the X-DAC’s USB interface.  Classical, jazz, or rock, what I heard is pretty much what my experience with other excellent DACs tells me is contained in the file.  If only my sample did high resolution files via USB, I could easily live with it using that interface alone.  My one suggestion to Rein Audio would be to soon offer a USB option that deals with native files at resolutions greater than 96 kHz, as folks committing to computer audio tend to be interested in pushing the resolution envelope.  In other words, I’m afraid that the 96 kHz limit may well be a deal breaker for some potential customers.


           For those who like comparisons, I was fortunate to still have on hand a comparably priced DAC, the Kingrex UD 384 and its sidekick lithium ion battery power supply, the UPower (together $680 USD).  For the comparison, I listened to the Kingrex via its USB input (its only interface option) and the X-DAC through its coaxial input, using the Kingrex as a USB to S/PDIF digital converter.  This arrangement allowed me to switch quickly between the DACs by simply turning the input knob on my preamplifier.  These two DACs sounded frighteningly similar to each other, especially in their tonal qualities.  Even though slight differences began to make themselves known, I’m really not sure if I could identify the individual DACs in a blind A/B listening session.  This is, of course, good news for folks in the market, as both DACs provide excellent sound at their price points.  Where they really differ is in terms of implementation and features.  The Rein Audio X-DAC is the hands-down winner in terms of interface and output options, whereas the Kingrex is USB input, single ended output only.  While the Rein has a traditional transformer-based on-board power supply, the Kingrex opts for an external battery supply.  The Kingrex also offers an asynchronous USB interface that can process native files at sampling rates up to 384 kHz, while the X-DAC’s USB is adaptive and limited to 96 kHz files.  Further, the Kingrex also doubles as a USB to S/PDIF converter, which the Rein does not; however, I easily give the overall build quality nod to the Rein X-DAC.  Here’s the deal:  you won’t go wrong with either unit when it comes to sound quality.  Pick the one that has the feature set you want and don’t look back.


           Just a few final observations about the Rein Audio X-DAC.  Late in the review, I received a sample of the Sound Performance Labs (SPL) Phonitor, a state-of-the-art headphone amplifier designed for professional mastering studios.  This thing is a real monster, but I quickly learned that it could serve as an excellent tool for evaluating DACs due to its incredible transparency and resolution of detail when coupled to a good set of cans.  To make a long story short, I remained as impressed as ever listening to the X-DAC via the Phonitor.  I just couldn’t seem to get it to mis-step, as it delivered the exact balance of resolution, harmonic purity, and overall listenability that I had consistently gotten with my “big” system.


           All in all, I’ve been very pleased with the Rein Audio X-DAC’s visit to my audio system.  It’s a great example of what can be achieved for under $1000 USD by offering great build quality, lots of connectivity options, and above all, lovely sound.  As I said before, saying good-bye is sometimes hard to do. 



For $780 USD, I’d classify the Rein Audio X-DAC as an excellent value; just the sort of thing Cheap Bastards who also like high quality should be homing in on.  With lots of input/output options, this is a versatile piece of gear that also sports very high build quality and good looks.  And yes, it does sound good; in fact, very good.  Good for getting better sound from your computer or as an entry level DAC in a moderate main system or second system.

Recommended to those who like a detailed but harmonically natural presentation in their music.  I’d advise prospective North American buyers to perhaps wait until a 110 V version is available for the sake of convenience. 


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