Nice sound, but issues
I got a N22 but had to return it. It sounded quite nice, but the one I got had issues. The volume on the left speaker channel was higher than the right by a little at all volumes. The power plug was loose-fitting, enough so that at random it would lose power. The headphone amplifier has very nice sound, but the level imbalance was much worse - at low volumes the right channel was completely silent and at louder volumes the right channel became gradually louder than the left. The volume knob and headphone jack were both quite crooked. So, quality control was an issue with the amp I had as well as the channel imbalance issues. I am aware of Audioengine's advice to reduce the volume of the source, but that just wasn't a good solution for me and didn't solve the headphone amplifier issue. In short - nice sounding amp, less than stellar quality control.
Pros: Class AB, sounds nice, headphone amplifier is very nice sounding, looks interesting, runs cool without fans
Cons: speaker channel imbalance, headphone amplifier channel imbalance, poor quality control