My Denon is only rated for 6 ohms and I've never had any problem driving M80s + VP180.
I have had the M80s without a sub for a year now and they have enough bass for any type of music, so does the M60s. The only thing you'll be missing is the LFE from movies, even though at high volume, the M80s still make my floor rumble smile

Bruno
M80s/VP180/QS8s/EP600/AVR-890
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"The problem is choice..."