Since the SC-63 uses a switching amp rated at 125 watts/channel it should be more than capable of driving those speakers to extreme levels. Comparing switching amplifiers to the analog class A/AB amps is not something I am well versed in but It would seem that the switching amp is more efficient in the use of power but if required to provide 125 watts to all channels at the same time continuously it might have some problems. Assuming the SC-63 can supply continuous power at 125 watts then the actual difference in sound pressure level compared to the 7700 is only about 1-2 db which is not very significant.