Dedicated circuits

OP:  There may be a little confusion because of 120 V 15A outlets.  It is legally acceptable to put these on 20A circuits, but this is the only place I know of where this is true. As I recall this is more to do with the likelihood of having multiple outlets on the same circuit, so you want a little extra current rating to support multiple appliances.

Anything rated for more usually doesn't share a circuit.

I think I know where the mistake in VA is coming from.  Too little understanding of the math around transformers.

For an ideal transformer (without losses) the VA on the input equals the VA on the output, however!! If the V on the input drops, V*A is less on input, therefore V*A is less on output.

Transformers are often used in voltage regulators, but they do their magic by altering the output taps.  Most linear gear is not this lucky, but most line level gear is well regulated so 20% voltage changes won't matter.  Amps are not so lucky.

PS - I have a modest 120W/channel integrated amplifier on a Furman AVR which lets me monitor line voltage AND see instantly if the taps are switching to compensate, as @dpop imagined amps do (they don't, but an AVR does!) .  I echo the sentiments that while the inrush current can cause significant sag, during actual playback actual current needs are small and I rarely see more than 2 V of AC line voltage fluctuations, even with the TV and Home Theater receiver feeding off the same line too.

Hey @dpop 

While you are correct that Watts = V * A, the way linear amps work (with the exception of Sanders' Magtech) is that the rail voltages WILL sag if the line voltage sags.  There's no adjustment feature without a voltage regulator such as a Furman with an AVR feature. 

Does this sagging matter?  Well, possibly.  I think this would be a good case study for Amir to do, to compare output linearity with input AC voltage on a linear amp. Due to the way current amplification works, and moderate amounts of feedback we normally pretend it doesn't.

@builder3

 I think you misread.  He states that the components have robust power supplies. I would interpret that as the build of the transformer, rectifiers and filter caps. 

He's also stated his amp is on a different circuit. 15A for source components is plenty.

If I recall, the Carver subs substituted power for size, so a ferocious amount of power was demanded.  Not that surprised.  :-)   A large diameter sub would fix that.

Zero benefit, significant risk and liability and not everything is a "dead short." Even if it is, in the time to trip the breaker anything not rated for the breaker's current is a risk. 

But sure man, ignore best electrical practices for a non existent audio benefit.

There's no audible benefit to a 30A breaker, and significant downstream risks. A downstream short in an AC cable, or outlets not rated for 30 A is a problem I wouldn't want to risk in my home.

The PS Audio PowerPorts are not rated for 30 Amps, only 20.  If that's what you used you should downgrade your breakers to 20A.