I heard about the Wadia 151PowerDAC from my friends at Magnepan, who make some of my favorite flat-panel speakers. They loved the way the 151 brought their fourteen-inch tall Mini Maggie speakers to life. That's great news, because when I auditioned the Minis at the factory last year (before they tried the 151) the speakers were hooked up to a massive Threshold stereo power amp. The Threshold/Maggie system was, by a large margin, the best-sounding desktop system I ever heard. Using a monster amp like that wasn't a practical solution for most buyers, but now with the tiny 151 amp Mini Maggie buyers have a more attractive option.
I really wanted to check out the 151PowerDAC (digital-to-analog converter), but I don't have the Mini Maggies at home, just my 6-foot tall Magnepan 3.7 speakers. Guess what, the 151 sounded incredible with the big speakers. It's a digital amp, but a very sweet-sounding one, with a warm tonal balance, yet there was no shortage of detail.
The 151 has four digital inputs -- USB, Toslink optical, and two RCAs -- you can connect a computer, games, streaming-audio sources, etc., to the amp. The USB input accepts up to 24-bit/96-kHz digital audio; the other three inputs accept up to a 24-bit/192-kHz input data rate. The 151's interpolation algorithm upsamples all incoming data to 24 bit/384-kHz audio, which is then sent to the digital amplifier. There are speaker cable binding posts, but unfortunately there are no analog inputs. Upfront you'll find an input selector, mute, phase and volume control buttons. The light blue LCD display isn't too bright, but if you find it distracting at night you can turn off the display with the remote. The 151 delivers 75 watts per channel into 4-ohm speakers, and 50 watts per channel into 8-ohm speakers. The nicely finished, all-metal chassis (available in black or silver) is 2.7 inches by 8 inches by 8 inches, and it weighs 6 pounds.
The metal remote is a step up from the plastic remotes that come with most AV receivers, even ones that sell for thousands of dollars. Wadia was founded in 1988, making it one of the first high-end digital audio companies. Wadia introduced the world's first integrated digital converter/power amp in the late 1990s; the 151 is a direct descendent of that design.
The 151 with the big 3.7 Magnepans wasn't an ideal combination, these power-hungry speakers need more oomph to fully strut their stuff, but up to moderately loud volume levels the sound was wonderful. I haven't heard the 3.7s sound better with far more expensive digital amps. Paired with the 14-inch-tall Mini Maggies and listening from a few feet away on a desktop, the 151's power will be more than adequate.
I also listened to the 151 with a few box speakers, including the wonderful Harbeth P3ESR speakers (review in the works), and that combination sounded very sweet. The 151 is the best-sounding under-$1,000 USB DAC/power amp I've heard to date. It's not just a desktop amp, it would be great in a small hi-fi system in a bedroom or office. Highly recommended.
If you would like to check out the Mini-Maggie speakers, but don't live near a Magnepan dealer, contact the company to arrange for an in-home trial.