late to this thread.......this comes up every 2 months or so, I advise people:
Check the back of your equipment or the owners manual (online for planning purposes)
It has this info, max current needs, here my EP2500 uses 9.5A @ 120V:
from my Denon 4308CI manual, (140w/ch 7 ch):
Power supply: AC 120 V, 60 Hz
Power consumption: 8.1 A
0.3 W (Standby)
add them up, be within 80% of the absolute load capacity of your circuit.
Some have said doing it this way you can go 100% of your circuit capacity, because each component in reality won't pull it's max load at same time, etc.
I error on safe side still for my circuit load analysis and usage.