Wadia Digital 121Decoding Computer
Input: AES/EBU with XLR type connector, Coax RCA, Coax BNC, Plastic Optical TOSLINK, USB 2.0
Output: (1) Pair Balanced (XLR), (1) Pair Unbalanced (RCA), (1) 1/4” headphone output
Dimensions: 2.7 x 8 x 8 in., 6.68 x 20.32 x 20.32 cm
Weight: 2.5 lbs. (1.13 kg)
Availability: online and through Authorized Dealers
A Decoding Computer
Wadia is the father of the decoding computer. Their first, the 2000 Decoding Computer, hit the market in 1988 and the company has continued to innovate introducing the digital music listener to the notion of the separate D/A converter (decoding computer), glass fiber-optic links, and the concept of jitter to name but a few. The subject of today's review, the 121Decoding Computer, is Wadia's newest assault on the state of computer-based music playback and I like the way it thinks. Even better, I like the way it plays.
The 121Decoding Computer is a DAC, preamplifier, and headphone amp. There are inputs for AES/EBU (XLR), S/PDIF (Coax, BNC, and Toslink), and Asynchronous USB all of which are capable of handling 24/192 files. Windows users who have been left behind by Microsoft's decision not to support USB Audio Class 2.0 are taken care of by the Wadia drivers that come on the included USB thumb drive. Mac users just plug in and play.
If we follow our digital signal from the USB output of our computer into the 121Decoding Computer, the first process of note that it hits is the USB Receiver [footnote 1] which is also responsible for the Asynchronous USB technology. This chip then hands off its signal but before it reaches the DAC [footnote 2] its gets to travel through Wadia's Field-Programmable Gate Array (FPGA), along with the non-USB data, which contains 8,256 logic cells (I counted, kidding) for a veritable DSP car wash performing a number of operations including buffering the incoming data into memory, upsampling using Wadia’s proprietary DigiMaster algorithm and filtering technology as well as applying Wadia's ClockLink jitter reduction technology for USB or Wadia's ClockLock jitter reduction for non-USB data. Once your de-jittered, scrubbed, upsampled, smoothed, re-clocked and locked data enters the "D" side of the DAC chip, its upsampled again this time to 32-bit/1.4MHz before the conversion to analog.
We've seen these kinds of heady heights heightened further in the Resonessence Labs Invicta DAC which upsamples all incoming data to the "50MHz domain". Since upsampling in general is still a sometimes controversial (aka misunderstood) subject, I asked John Paul Lizars, Director of Marketing for SUMIKO and my contact for this review, if he could talk about the sonic benefits of the 121's DigiMaster algorithm and filtering technology which preforms the first phase of upsampling. John Paul passed my question along to John Schaffer, Wadia's President, who was kind enough to provide the following answer:
Digital filtering systems are used in most DAC's. They increase the sample rate of the source data so that the analog filter can be implemented in a way so that the filter itself will not introduce audible distortion.
The DigiMaster system in the 121 is a software based solution that runs on a DSP block configured in the FPGA. DigiMaster uses a synchronous interpolation process to preserve the entire original signal and provide a higher data rate. What is unique about DigiMaster is that it is a predictive algorithm, it uses Spline math to calculate a curve that will fit between the known data points. Essentially it is attempting to rebuild the original wave form in a way consistent with how we understand wave propagation. With the 121 we are able to achieve 32 bit precision in the calculation used to derive the predictive sample points. That allows us to calculate the predicted sample without requiring intermediate rounding, or truncation, steps in the calculation of the new sample. The improved precision results in an audible sonic improvement. The DigiMaster system provides balanced performance, producing excellent results in a wide range of tests, including phase and impulse response, which are critical to accurate and realistic reproduction of music. The sound of our solution as implemented in the 121 we feel is very natural and provides a heightened sense of "Being There".
Interestingly, Wadia offers up their preferred method of connectivity in the manual as follows (in descending order of performance): USB, AES/EBU using XLR connector, Coaxial cable using BNC connector, Coaxial cable using RCA connector, TOSLINK plastic-optical cable. Most of my listening, which we'll get to soon and see how close to "being there" I was able to get, is based on the USB output of my MacBook Pro running Pure Music and Audirvana Plus.
The 121Decoding Computer's volume is controlled in the digital domain in "(120) 0.5dB steps" for a 60dB range (I know you already figured that out but I thought I'd save you the trouble). There are six blue LEDs on the 121's front panel that give you a ballpark display of your volume level (you couldn't very well have 120 LEDs). Since I use an integrated amplifier, the Leben CS-300XS, I mostly kept the 121's volume pegged at its max level except when using the headphone output.
Owners can also adjust the output voltage level by choosing 4.0v, 2.0v, and 1.0v to match their system's sensitivity. Three of those same six LEDs used to show volume level also indicate output voltage level when you are making adjustments to it with the included remote. Those same LEDs also serve triple time as balance indicators when adjusting left-right balance with that same remote. Since the 121 does not include any controls on its chassis, you'll want to Velcro that puppy to something that you never lose. Our dog Heidi volunteered but that seemed all wrong so I just followed my two-place rule—only put that remote in one of two places.
But doesn't digital volume mess with the bits making them less than perfect? Wadia explains their use of digital volume control in the 121 manual as follows:
The volume level can be varied in the digital domain by means of mathematical manipulation of the signal, eliminating the distortion and noise that are inevitable with even the best analog volume controls. While conventional thinking indicates that reducing the volume digitally can sacrifice low level resolution, Wadia has created an innovative solution. Wadia’s patented digital filtering algorithm produces a 32-bit output. This high-resolution signal is then used in the computations that in turn reduce the volume level. This new signal is fed directly to the DAC chips. Through this innovative method, the Wadia 121Decoding Computer maintains high resolution even at the lowest volume control settings.Other functions offered via remote include input selection, mute, phase (the 121 inverts absolute phase in the digital domain), headphone output sensitivity (low and high), and display brightness (two settings - really bright or not quite as bright). The basic replay function buttons (play, pause, stop, next/back, and eject) work when using a matching Wadia CD transport for those old-school disc types. To fill out our functional picture, the 121's face also includes six LEDs indicating the source selection and six more that indicate the incoming sample rate (44.1, 48, 96, 176.4, 192kHz).
Early production 121 units included two headphone jacks, 1/8" and 1/4" (as I write this the Music Direct website is still showing this version) but that 1/8" jack was replaced with a power indicator LED. The reason for this change from 1/8" headphone jack to always-on blue LED was also explained by John Schaffer of Wadia:
As it turns out, not all 1/8 " headphone plugs are the same. We learned that if the barrel of the plug was molded a certain way then the plug would not seat properly into the jack. A customer might experience an intermittent connection when using their headphones with the 1/8" headphone output on the 121. Consequently we made the decision to remove the 1/8" headphone jack in order to ensure that we would not create a less than positive experience for any customer.I'll have to rib Wadia for this decision to replace that 1/8" jack with a power indicating LED since you cannot turn the 121Decoding Computer off without unplugging it. Which kind of relegates that LED to permanent no kidding status (I swear I think it winked at me once or twice) especially seeing as the volume level LEDs also stay lit. That's correct, there is no on/off switch to be found on the 121 and Wadia explains that the 121 sounds better when left on. Thermal stability is their explanation for this phenomena and Wadia offers this additional powerful advice in the 121 manual, "A new unit will undergo more dramatic changes when power is applied for the first time. If you turn off your Wadia 121Decoding Computer for more than an hour, you will find that the unit will undergo a similar, but less dramatic improvement once power is reapplied."
I find the look and feel of the 121 and the included aluminum IR remote to be solid and reassuringly well-made even considering the 121's near-feather weight. And the main reason its so lite is because Wadia uses an external switching power supply in the 121Decoding Computer. Gasp! Upgrade! The horror! I did not try any after-market power supply upgrades with the Wadia 121 mainly because I didn't feel the need to and to my mind things like power cord swapping and power supply 'upgrades' are largely system setting dependent. But this certainly puts the no power switch decision into finer focus.
Trickle Down Works
Even though the 121Decoding Computer is the relative babe in Wadia's line of decoding computers, it performs like its all grown up. This is another instance where I pretty much fell under the 121's spell from the first few sweet notes it sang. The 121 passed every test I threw at it with flying colors including the did-I-sing-along test (yes), the did-I-feel-sad test (yes), the ever-embarrassing to admit did-I-dance test (yes), and the most important of all the did-I-play test (Oh yea). And I would not highlight a particular aspect of the 121's sound for all of this testing success as it strikes me as exceedingly well-balanced.
I'm going to break a few of my unwritten rules in one shot and share that there's a CD/rip I use repeatedly as a test track and have for years. There I said it. Actually there are many of these but this particular one is odd in that I only really enjoy listening to this one track. The rest of the CD leaves me with a touch of saccharine-overdose. Even this one track, Percy Grainger's arrangement of Ravel's "La Vallee des cloches" from In A Nutshell [EMI 7243 5 56412 2 9] has its ups and downs. But overall, I find it to be a lovely piece/place and the bells in the title ring out in all manner of voice, shape, and size and are even laid out in space (as in a valley). This song's presentation can suffer any number of digital deaths including ring-castration, edge enhancement, foreshortening, timbral sameness and on and on. The 121 threw everything encoded in the associated bits of "La Vallee des cloches" out into my listening room making it feel at once vast and imbued with, wet with, emotion. Stunning, really.
This ability to turn test track into emotional experience is ideally what I want from every piece of hi-fi. If I stick and stay stuck in test mode something is wrong. In terms of methodology, I listen over weeks and if possible longer for many hours each day to help avoid the variances and fluctuations within me and my listening moods. Kinda like a switching power supply, I like to leave my listening on over extended periods. And the 121 never disappointed, never revealed a sonic edge that stuck out to distract me from listening for pleasure. I was never jerked back into test mode (I hate when that happens). To put it as simply as possible, the 121Decoding Computer makes digital files sound like sweet, natural music and that is a conversion process to write home about.
Some of you may be wondering about the 121's bass response since there's this notion that a piece of hi-fi gear has to have some size and heft to it in order to reproduce bass convincingly = big power supplies, big iron. The tuba theory. Did you ever notice in those wonderful old doo-wop groups that the dude handling the deepest nearly inhuman-sounding subterranean notes was typically rail-thin? Rest assured the 121 can plumb the depths even without an anaconda-proportioned power cord and what's more bass is controlled, dimensional and presented as part of the whole. This is also partly responsible for the 121's dynamic snap appeal. Nothing lags or gets bloated or slow. Music moves.
I also took the headphone output of the 121 for a spin with my Audio-Technica ATH-W1000s and when music was not playing things were silent (as expected) and depending on the musical selection things were more and less silent (as expected). I have to admit my preference for listening in-room and part of the 121's strengths is how convincingly it presents music in-room which is to say its physical, solid if a tad tightly packed and missing an iota of air among and around musicians (where this kind of thing exists), and dare I say muscular.
A Musical Contender
To my way of listening, the Wadia 121Decoding Computer jumps right onto my short list of recommended components. It strikes me as being at once refined yet not overly resolute, with a voice that sounds like music. Sweet music. I enjoyed every listening minute spent regardless of the recording or its associated quality. That said, well-recorded music can be especially stunning through the 121 so whether you like to stroll through the valley of the bells, swing with Ella and Louis, sway with Bob Marley and the Wailers, sing along with Tom Waits (as bad as me), sink into a sweet sullen state with Schubert, Sinatra or Syd Barrett, or raze the roof with Einstürzende Neubauten or John Lee Hooker, the Wadia 121Decoding Computer may very well have your ticket to ride.
Footnote 1. If you search around the internet you'll find references to (and a video of the insides of the 121 without the stickers from a Wadia dealer) the manufacturer of the USB Receiver chip used in the Wadia 121. One dealer claims this USB receiver chip is from XMOS and while this seems likely I could not get verification from Wadia who'd I imagine feels this level of detail is practically irrelevant. And for most intents and purposes I'd have to agree. The notable exception being reverse engineers (and good luck with that).
Footnote 2. The DAC chip used in the 121 is reported to be from the SABRE32 Reference line. This information also comes via a dealer comment on a forum so you can take it for what its worth. See footnote 1 for more.
Also on hand and in use during the Audiophile Desktop review: Mytek Stereo192-DSD DAC, Schiit Bitfrost DAC, AudioQuest DragonFly USB DAC.