Class-A Amplification and 15 Amp Outlet

I currently listen to a class A integrated amp plugged into 15amp wall outlet without any issues. DAC, CD transport, streamer, turntable and pre on same circuit. 

A 15 amp wall outlet is sufficient for the amps you mention.. And also for the DAC and preamp.

Should you wish to research for yourself, understand Ohms law as it explains the relationship between volts, amps and watts. Add up the watts drawn by each component as if they were one (this might be on a label at the back along with the volt and phase rating, or in the specs).

Different countries have different voltages so this is why you have to do the calculation for yourself, should you wish to satisfy your curiosity. 

Look at the idle and power rating for the amps. A 15A outlet is rated for about 1800 VA I believe, so long as the amp plus your accessories stay above this you stay well below that you’ll be fine.

You might want to swap to a better outlet though, especially if this is an old house. See more here:

You may also want to consider a conditioner with voltage regulation to ensure the voltage doesn't sag:

Of course, you can  also have a dedicated circuit with 12 gauge wiring and convert the line to 20 Amps. The beefier wiring, above all, will improve power delivery under stress.  If your circuit is going to be over 1,000 VA most of the time I'd suggest it.

Watts devided by volts = amp draw.  The Pass XA160 you mention draws 600 watts, which equates to 5 amps (600 watt devided by 120 volt power supply).  My entire system (Hegel H590 amp) draws less than 2 amps when playing music.  You should be fine on a 15 amp breaker but you need to calculate the total amps required before choosing equipment?