I have not listened to the WA22, but the Sonett is one of the finest amps I've listened to with the HD-800. I listened to one again today (

) and had the pleasure of hanging out with Donald and a lot of other great Head-Fi'ers. Perhaps the WA22 is excellent, but I don't think you could go wrong with the Sonett. Aside from the Sonett's sound, I particularly like its build quality, choice of power supply and use of the exceptional (and affordable) 6H30. The 6H30 is excellent for preamps and headphone amps, but seems somewhat neglected by manufacturers. It is very much worth considering.