I heard the Wadia 121 last night at my local dealers computer audio presentation. All of the equipment was high end except for the DAC's (Rockport Miras, Electrocompaniet Nemo amps, Electro pre, and top of the line Transparent cableing all around.) The shop is also an Arcam dealer so they A/B'd it continuosly with the Arcam D33 ($3200) DAC. They were using a Mac mini with USB, Amarra software and an Ipad. We listened to ripped CD tracks, Hi Res downloads from HD Tracks and some MP3's (no streaming files which I realy wanted to hear!). Even though the Wadia was not yet burned in, most, including myself, thought it was easily as good as the burned in Arcam. Even the MP3's sounded good!
I was very impressed as were all of the people who were in attendance. I'm definately considereing this!