Wadia 151PowerDAC
If testing the Wadia 171i iPod Dock felt somewhat alien, given that my days with an iPod have long gone, reviewing the Wadia 151 PowerDAC - a combination of high performance DAC, and a robust 'digital' amplifier - was a more natural assignment. It was also exciting in that bearing in mind that Wadia is known to be strong in producing digital players, a fact that my recent audition of the 381 CD player confirmed, I was of course tempted to learn and hear what kind of amplifier it could do.
The 151 is an integrated amp with digital inputs only. There's no other way to run this amp but through its own internal DAC. Forget analogue sources. That may sound unfair but, hay, the 151 is a genuine Wadia product. The idea is that the owner connects his CD or DVD player or some other digital source - I used Audiomeca CD transport, Marantz CD player, and a Denon DVD player - digitally to the 151's digital input, and the amp to the speakers. Easy and simple. The other digital coax inputs is no doubt reserved for identically sized Wadia 171 iPod/iPhone dock/transport. Wadia's own coaxial cable comes along. The rest two digital inputs are an USB port and an optical Toslink.
The size of the 151 suggests that the amp is meant on a table next to a computer or in a small hifi-system with medium size or smaller loudspeakers. Not that the 151 could not run bigger speakers: 95% of the time its 25/50 Class D (fast switching transistor chips) watts (8/4 ohms) were enough to control the 4-way Dunlavy Athenas; the 5% refers to dynamically powerful sections in music when I felt some weakness by the side of the 151. I felt that the 151 was more at home with 2-way Dynaudio standmount loudspeakers, for example. The weakness came out not in the amount of bass itself but in some kind of elusive inconsistency of the bass performance, and this was less prominent with lower volume levels and smaller speakers.
To the extent possible within the 1250 euro price, Wadia has put into the 151's DAC part the digital techniques that it has applied to its pricier models. That includes, eg., Wadia's DigiMaster and DirectConnect -techniques. DigiMaster is Wadia’s patented upsampling software that runs on high powered Digital Signal Processors (using a synchronous interpolation process, and 12th-order polynomial Spline curve fitting). With the DirectConnect techniques the signal from the DA-converter is transferred directly to the power amp section bypassing many analogue circuits. The digital volume adjustment is traditionally Wadia's area of expertise. Volume setting, input selection and phase inversion are done either from the front panel buttons ot from the compact remote.
The WADIA 151PowerDAC's DAC (24bit/384kHz upsampling) accepts up to 24bit/192kHz data via S/PDIF and 24bit/96kHz via its USB port. 24/192 2L BlueRay music discs sounded fine through the 151, but so did 24/96 discs/files, RCA or USB.
Sonic qualities
The most striking and fascinating feature of the sound was that the 151PowerDAC managed to sound as it's constructed: pure, clean, transparent digital front end, colourless less startling Class D power amp stage. Irrespectively of which loudspeakers I used, the sound of the 151 possessed exceptional purity, showing no sign of distortion whatsoever. This was not warmish or lavish purity. It was cool and dry purity, yet without unacceptable bright tones. Piano music came out boldly and tonelessly respecting nicely the music's dynamic nature.
The said purity added to the impression of details being present in the sound as exemplified by some well-recorded violin samples (eg. the way in which the violin sound faded away into silence was great). Interestingly the purity also appeared to add certain concreteness to the sound. The 151 didn't make the overtone structure of a cello richer and more natural sounding, as some quality tube amps tend to do, but by increasing the cello's and vocalists' face value in the overall sound, the 151 made them sound more reachable, to be more on the skin.
As compared to digital Silicon Arts Si2 pre/power combo, the Si2 mix sounded more fragile, more "complex", more 3D, the focus of the sound staying more behind the center line. The Wadia 151 had a slightly better bass, better power and dynamics. Both sounded pure albeit the 151 in the different aforementioned way. Neither amp sounded boring.
As compared to my tube combo (Dynaco/DIY 6V6), as well as against the 4-6 watt EL84 single-ended Mastersound Piccolo, the 151 left less air around the instruments, sounded less 3D and slightly colder, resembling in this particular regard more contrained sounding transistor amps. On the other hand, the Wadia 151 was quieter, was more polished and cleaner sounding, had a good sense of pace, and was somewhat more effective in the bass. However, as regards timing and quality of the bass, the tube amps were equal to the 151.
One interesting, and as far as I can tell, also a relevant difference between the 151 and the tube amps was this: when volume of the Wadia was increased, the sound got uniformly louder. Whereas with the tube amps turning the volume knob up only increased audibility of certain elements (instruments) in the sound, leaving others with less attention. For some reason I felt the latter way was the right one. This may be one of the matters with respect to which Class D amps (PWM) have to pay for their technical advantages.
The Wadia 151 offers truly handsome and addictive listening for those who value more than anything lack of all sort of dirt in the sound. This purity and neutrality has, although not much, its cold and mechanical side. That's why I'd choose loudspeakers for the 151 that add some positive colour and soulfulness to the sound while preserving its overall purity.
The competition among AmpDACs is tough nowadays. The success of the Wadia 151 PowerDAC as a central unit in a standard Hi-Fi system is partly limited by the fact that it lacks analogue inputs. But imagine someone who's got the Wadia 171 docking station for his iPod, is a heavy laptop user for sourcing music, and who occasionally listens to his CDs but wants to improve the sound of his mid-fi CD player. Is there a better choice than the Wadia 151 PowerDAC? Hardly.
Wadia 151 PowerDAC, 1250 euro.