I don't have an amp to look at so I can't see a fuse either. The labeling for the power consumption is usually printed near the fuse. Either way is just easy I guess. However, the fuse is rated slightly higher than it would actually consume at peak power, or else it would never reach peak.
Maybe I shouldn't have mentioned the 120V 60hz part since most list the watts anyway. It's just that some devices are designed for 120 or 240 V operation and are thus labeled for current consumption at each voltage. I would like to know what it says at 120 V because that's what I'll be hooking it up to.
10 amps at 120 V is 1200 watts. The same device would only draw 5 amps at 240 volts. That's why I specified the voltage. If you find the watts printed,and it's more likely you will, voltage doesn't matter.
50 amps would allow for 6000 watts! 6000/4=1500 watts average for each hypothetical amplifier. I hope they don't draw near that much!
When I said the biggest the store had was 50, I was referring to a 50 watt amp.