I don't own, nor have i heard, that combo - but i did recently ask a very similar question:
http://www.head-fi.org/forums/f5/otl...grados-468335/
The consensus seems to be that amps like the MKIII may sometimes "synergise" with low impedance cans like grados, but there are very valid technical reasons why it is not as good an idea as, say, a solid state, hybrid or transformer-coupled amp. It comes down to current supply, which low impedance cans need. Then again, many people seem to have very successful pairings.