Simple. Powerful. Dynamic. Clean. This is the upgraded 'B' version (check serial number - actually I don't know what this affects, but I noticed someone else thought it was important) and includes the large OBH-2 power supply.
Best review I can find is here on Audiogon: http://tinyurl.com/7ucylye .
Used happily for the last few years with my Grado 325's. Also selling my OBH-12 on Audiogon, downsizing to an integrated for domestic tranquility.