Electrical question

and varying amounts of capacitance...the dynamics of music don't have a linear draw on the power supply either 

The OP’s house was built in 1995. Minimum overhead fed electrical service is 100A @ 240V. That means each of the two legs 120V to neutral loads is good for up to 100A each.

200 amp overhead fed electrical services were common place in 1995 as well.

Underground  fed electrical services even in 1995 were required by many power companies to be 200 amp electrical services. 

    A 120V 15 amp load ain’t squat in the scheme of things.

FWIW our over the range microwave/ hood vent fan unit is rated at 17.7KW. 1700W / 120v = 14.17 amps. My 200A electrical service doesn’t even care when it’s running. My central air outdoors condensing unit draws more than that at 240V. Even that load is minuscule to my 200 amp electrical service.  

Interesting how no one seems aware that their gear have regulated power supplies.

My ARC power amps do not have DC high voltage regulated power supplies. 

I suggest you check the archives for posts of @atmasphere how voltage drop affects the performance of a power amp.  

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Regulated power supplies are rarely used in amplifiers and the voltage on the rails is direclty proportional to the voltage on the AC.

Having said htat, that's an unusually high drop.  Your house's age may have something to do with this but modern code has a separate circuit just for the microwave.  If you are still seeing that kind of drop, measure the neutral to earth.  If it's more than 2V you have a separate issue which is a bad neutral.  I use these because they do both voltages at the same time.

HJaving said all of that I use a Furman voltage regulator to keep my AC within 5V at all times, but it's not for bad wiring.  It's for the 2 heat pumps turning on and off and seasonal variations. 

A quote from Vinnie Rossi audio site see below:

’’With active power factor correction (PFC) and superior regulation and stability, the power supply ensures maximum performance regardless of AC mains quality. Housed in a fully enclosed compartment precision machined into Brama’s solid aluminum body, it is fully grounded and isolated from the audio circuitry, performing like a highly-responsive, well-tuned engine.’’ See Vinnie Rossi here.

Mike