I'm a little late in joining this thread but I thought I'd chime in. I have the Sheer HA-006+ Plus Edition and it drives my ATH-AD2000s spectacularly well. I was lucky enough to snatch it for $180 used with a dent in the faceplate.
I haven't been visiting Head-fi lately because I'm so happy with this combination that I've reached the end of my search, at least for now. I did modify it a bit though. I shorted the feedback resistors for each channel to give it unity gain and installed a stepped attenuator (search "New 21 Step Attenuator Potentiometer 10K Log Stereo" on eBay for the one I used- it fits perfectly if you solder some resistor leads to the contacts). Each step is about 6dB and I've mapped keyboard shortcuts to switch between 0dB and -3dB in fb2k to double the number of steps.
Edit: Just to give a better idea of its performance, the HA-006+ handily beats my McIntosh 1500 with the ATH-AD2000s- and the McIntosh is the best stereo receiver I've ever had the pleasure of hearing. The McIntosh still has an edge for my HD 595 and HFI-680 but the Sheer/AT combo is unnaturally good.