The previous power supplies are not strong enough in the older Onkyo's to drive the 4 ohm load of the m80s at loud volumes for any length of time. The newer ones you are looking at are supposed to have better power supplies to drive the lower resistance in the M80s. I have read a few reports of the Reon and lip sync issues with the Onkyo's but that was when they were first released and I would think it has been rectified by now.

Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70