My experience is, you can't have enough power.
I've been running 5 * 200W in my smallish 4x4m leg-of-a-u-shaped-room and even then the bass was so much more controlled, I couldn't believe it.
Also there was no congestion at loud levels anymore, I remember listening to Mahler's final parts of the 2nd and 8th symphonies made the voice(s) stand out very clearly from the orchestra, with no distortion at all.
So if you can spare the cash, go for the 7700!
It's a bargain really compared to the competition.
I would order soon, because there's a price increase coming up I believe.
Barend