I expect those Rotel Michi's would eat the RB1070 for breakfast.
Actually, we've given the RB1070 back now so I suppose we can tell you what we learnt...
Well, it was generally more refined than the stock RB976 (6 channel AV amp) that we bought to replace it. It was good, refined, clean, powerful, good imaging, decent bass and not in any way hard or glassy as we've found they could be.
BUT, once we'd been into the RB976, fitted a IEC mains inlet, proper power cord and some minimal and subtle (although not especially cheap considering the tiny amount we used) re-wiring, the RB976 walked it. We were running it bridged (3 channel mode, of which we were using 2), it could do everything that the RB1070 did, but had a slightly less ponderousgait, but had real grip and slam and interest.
Is the RB1070 good for 500 quid? Yes, we were impressed, but at always there's more than one way to skin a ***** and there are better bargains out there.
WM says you want valves though?
Cheers