Ken Taraszka M.D. is an anesthesiologist by trade based in Tampa Bay, Florida. Ken is also a professional audiophile and home theater writer specializing in AV preamps and all facets of the audiophile market. In the past, Ken has been a staff writer and editor at AVRev.com. He has also at times been a frequent contributor at AudiophileReview.com.
When you discuss high-end digital audio, Wadia is a name that will always come up in the conversation when talking about high-end digital products including CD players, DACs and beyond. Known for their classics like the 861, which are still considered by many to be a statement piece, the company has been a front-runner in the world of digital music reproduction for years. While they are known most for uber expensive, cutting-edge products, they have begun to shift gears as of late. They are the first company to be licensed by Apple to produce a device (the 170i Transport, also reviewed) that allows a digital output from any iPod or iPhone with a dock connector. The subject of this review is the new 151PowerDAC mini, a tiny device that offers a stereo amplifier and DAC in one tiny package all for a retail price of just $1,195.
The new PowerDAC is an amazing little device, and when I say little, I mean truly physically small by audiophile standards. The PowerDAC measures in at eight inches square by two inches tall and weighs a mere six pounds. When I first saw it at CEDIA in September of 2009 I knew I needed to get one in my hands, as there were so many applications where a device like this could fit into my life. The PowerDAC accepts only digital inputs, and has two coaxial, one optical (TosLink) and a USB input, and is capable of accepting 24 bit/192kHz feeds (the USB only does 24-bit/96kHz. No matter what sample rate the feed is, it will upsample to 24-bit/384kHz using a spline interpolation algorithm to reduce error and create reportedly the most accurate representation of the original music. The unit keeps the signal entirely in the digital domain. The Direct Coupled digital volume control then adjusts volume before sending the output to the conservatively rated digital amplifiers, which are rated at 25 Watt per channel into 8 Ohms and 50 Watts per channel into 4 Ohms with quoted dynamic power of 200 Watts per channel.
The PowerDAC perfectly matches the 170iTransport, which Wadia was kind enough to send along for this review. The two stack on top of each other for a total height of four inches, making one of the coolest looking stacks in audio. The construction is solid and despite its small size, the unit is pretty dense. The case is sleek and modern with rounded edges and attached, spiked rubber feet; the same feet of the iTransport fit into mated impressions on the top of the unit keeping them both lined up when used together. The 170iTransport includes a coaxial digital cable to connect to its PowerDAC brother.
A cool blue display is on the front left of the unit. On the right are buttons for input, phase, mute and volume up and down. The rear of the unit is also pretty clean with two pairs of large, solid five-way binding posts on the right, with the two coaxial inputs above the optical and USB ins. The power adaptor and power switch round out the rear. The PowerDAC uses ultra-efficient digital amplifiers and the display is LED backlit to further conserve precious energy.
The unit comes well packed in a small flat box and includes the power cord, metal remote and batteries as well as an instruction manual and a brief history of Wadia. I was surprised how small the box was and just how dense the unit is upon unpacking, and was impressed to see the binding posts and RCA connectors were all gold plated and seriously robust. I have reviewed speakers costing ten times what this unit costs that had far lesser binding posts than these on them. Despite the small size of the unit, the inputs and binding posts were well laid out and easy to access. The remote is typical of audiophile gear: it's heavy, all metal and generally not very user friendly. The remote is a smoothly rounded shaft of black aluminum with buttons arranged in two vertical columns; all the buttons are the same size and shape and it is not backlit. The good thing about the remote is it also controls any Wadia transport, including the 170iTransport, so it can control your iPod or iPhone when in the 170iTransport or any disc in any other Wadia transport.
The PowerDAC is designed to be the hub a digital system, so I initially set it up on my Mac Pro's computer desk with a USB feed. I ran several speakers off it, initially my Kef 5005.1 speakers from my bedroom system, then I moved onto a pair of Definitive Technology ProMonitor 1000's. Setting up the PowerDAC was a snap and took only a few minutes to complete. To connect it to my Mac Pro desktop computer, I simply ran a USB cable from one of the front ports on the computer to the PowerDAC, ran a pair of wires to the speakers, connected the power cord and turned it on. A quick trip to the Midi settings on my computer to set the output preference to USB and I was up and rocking in no time. That was it.
I fed it MP3's, AAC files and mainly AIFF files from my Mac Pro, Mac Book Air laptop and an Oppo BD-83 NuForce Edition as a transport. After a couple weeks of near continuous playing on my computer desk I took it to my reference system and used it to power my Escalante Fremonts via Transparent Reference XL speaker cables, who's large spade connectors easily fit into the massive binding posts. In this system I used my Mac Book Air with AIFF files and used both an old printer USB cable and a Transparent Performance USB cable to compare and again used the Oppo Nuforce as a transport. In this system the Wadia 151PowerDAC mini was run off its own dedicated 20 Amp power line.
I went against my prejudice and played Dianna Krall's Stepping Out (Justin Time Records) from my computer in AIFF files. "Straighten Up and Fly Right" gave me powerful keyboards while the standup bass had great depth to it. The vocals were smooth and sultry without any edge or glare. "Between the Devil and the Deep Blue Sea" showed amazing speed and dynamics for such a small amplifier and kept good separation of the keyboards, bass and drums. The piano could be lively and powerful yet could be delicate when the piece called for it. When I reran this track using my Escalante Fremonts, the sound was still smooth and engaging but the midrange and upper end just didn't have the air and space I am used to in this system, although the bass was amazing for such a little amplifier. Wadia recommends good cables, and I must say to my ears the Transparent USB cable did improve the sound, giving a more open presentation over my dated printer USB cable.
When I had the 151PowerDAC connected to my computer I listened to almost any type of music at any volume. One day I was listening to The Cult's Electric (Warner/WEA). That is an album that always reminds me of college parties so I was cranking it up some. From the start of "Wild Flower" I was amazed at how well the little PowerDAC handled bass even to pretty high volumes. The bottom end was far better than I expected from its low power rating. The bass was a touch punchy but even at high volumes kept up with the rest of the sound. At higher volumes the upper end was a bit compressed, which sort of confused me as the bottom end stayed tight. On "Electric Ocean" the bass was still punchy yet plunged quite deep. Guitar riffs were energetic while the vocals had the eeriness I expect of this band. During high volume listening my desk was actually shaking from the bass this little amp put out through the Definitive speakers.
While listening to Dire Straits Making Movies (Warner Brothers/WEA), the subtlety of the guitar on "Romeo and Juliet" was well portrayed while the vocals were well placed and clear. The drums had a little more punch than I'd have liked on this track but it wasn't off by much. The energy of "Expresso Love" was excellent. The riffs of the guitar were lively and had great texture to them while percussion was solid and went to depths I had grown to expect from this little piece. Keyboards floated across the soundstage, allowing me to get lost in the song.
I recently joined the B&W Society of Sound and downloaded Peter Gabriel's Scratch My Back in 24-bit 96 kHz FLAC that I can use with Songbird on my Mac computer as long as I change the Midi settings to output 24-bit 96 kHz. Peter Gabriel is an interesting musician and his music can run the gamut. This album is slow and powerful and from the opening track of his cover of David Bowie's "Heroes" the strings were powerful and moving while his vocals came across clearly and with a great breath. The piano on "The Boy in the Bubble" had a beautiful yet subtle intensity that made the song amazingly powerful. "Listening Wind" starts off with harsh strings and adds in deep bass and Peter's edgy vocals and all were melded together into an intense combination that flowed and ebbed as the intensity of the song played up and down and the PowerDAC showed all the power of the song. This is an album to buy if you don't already have it and one I will be listening to a lot, thanks to the quality of the tracks. I compared this to running it off my iTunes via 16-bit Apple Lossless and the sound was much more open and spacious with the higher resolution recording and the bass had better depth and control as well. The difference wasn't subtle and now has me running two music programs on my computer to take advantage of the high-res downloads I've gotten from this service until Apple releases an iTunes that will handle these high-resolution tracks.
Competition and Comparison
Those looking for a high-end computer audio system have a few other systems to compare this piece to. The NuForce Icon HDP ($449) is only a DAC/preamp and headphone amp but adds analog inputs via RCA stereo or mini jack. Another unit to look at would be NuForce's Icon-2 at $349 that has analog stereo via RCA and USB inputs but also adds a headphone amplifier and 30 Watts per channel power output into 4 Ohm loads, so significantly less than the Wadia. Larger units include products like the Peachtree Nova amp that runs $1,219 that adds the ability to use a tube or solid state preamp with its 80 Watt per channel amplifier, though it is much larger, on the order of a typical component so will take up much more desktop space. For those looking for top tier performance there is the Benchmark DAC I HDR for $1,895 that also has an analog input as well as a variety of digital inputs, but no power so you'd need and amplifier as well.
The Wadia 151PowerDAC mini is an impressive piece of kit, but it is limited in power so it will require pairing with efficient speakers and simply isn't designed to power a large room unless you have truly sick (100+ dB) efficient speakers.
One of the things that makes this piece so unique is that it keeps the signal in the digital domain until the final output stages, which is kind of a downside as this design will not allow for an analog input. If you need one or more analog inputs, the PowerDAC isn't going to work for you.
The remote is typical of audiophile gear. The buttons are aligned in two vertical rows and there is no way to tacitly feel which button you need, plus the remote isn't backlit. Physically, the remote is solid enough to use for home defense should you need to. I could see somebody using a Pronto or Harmony with this unit.
The Wadia 151PowerDAC mini is a really cool piece of gear that has a lot of applications in the modern digital world. I can see this as the center of a dorm, or apartment system based around a computer for audio but it can also work with cable or satellite TV and a gaming system or two thanks to all of its digital inputs. The sound of the unit is smooth and pleasant and thanks to Wadia's experience with digital, is never harsh.
The limited power output of the amplifier section will require you to mate the PowerDAC with efficient speakers or use it in a small room, or for nearfield listening as I did for much of my time with it. For me the biggest plus to this piece is the size of the unit itself. The 151 PowerDAC mini sat under my monitor connected to my computer and it took up almost no desk space, yet made a huge improvement in my desktop audio system. After I used it in my main rig I returned it to my computer and this time rested it atop my Mac Pro tower. Not only did it fit perfectly, it matched the aesthetics of the Mac tower and allowed me to further clean up my desk. I have speakers around my pool and the wires come into the house in a strange place where a full sized component would be odd, yet I easily could live with the PowerDAC on a shelf and most people wouldn't even notice it there.
I spend a lot of time at my computer, so the addition of a new DAC/amplifier to my desk was a welcome change. I have had a multitude of computer speakers over the years, but it was nice to step up to a more conventional system for my desktop and the improvement in performance was huge. What really impressed me most about this piece was just how well it handled bass, whether on my computer desk or in my reference rig. The bottom end was clean and tight, handling the lower registers extremely well given its power rating. The use of high-resolution recordings further elevated the performance of the 151PowerDAC mini and gave exceptional sound for such a small piece. I really enjoyed my time with this piece and was so happy with it I bought it when the review was over and now enjoy my computer system more than ever.