Well I got mine today. Initial impressions are good. It too 11 days including weekends. Using it with my Sr 325's.
Bass has alot more punch to it. Not overpowering in any way and not bloated just more punch.
Mids sound a little more full but not much difference.
Treble is another story. It seems to be a little less defined. Biggest notice was that rapid cymbal hits seem to meld together. I know its the nature of the headphone and this seems make it a little worse.
All in all I think its a great starter amp. Its silent up untill the 12'oclock setting and a little static can be heard. We will see how it burns in. Also sound stage seems to be better, its too soon to tell though.
Your Grados should really appreciate a good 6922/E88CC substitution.