I've had the 7700's predecessor, the 770, in a semi-large (25X 16) listening room/ht foe about 9 years now. The system gets about 12 hours of service per day at reasonable levels and the 770 has never so much as heated up while providing sublime performance.
I'd recommend this amp to anyone who is not running a rave in their spare bedroom , and mabey even if they are.
The 7900 is pretty sexy, but I can't imagine where you'd need more amp than the 7700 in a non-comercial setting.