It's a long story, but after a forced upgrade of my "not to code" electric service, which moved my to 200A service, I came out with an unexpected benefit that my large audio system could reap immediately. More SPL and effortless impact at all listening levels.
I thought it might be expectation bias altering my judgement, so I used the benchmark SPL test recordings that I based my original readings off of. For instance, when signal present lamps light, the power from each amplifier is 3 watts/channel. At that level, with the old power feed, the SPL was 129dB. With the new power feed, I'm seeing a solid 132dB with those signal present lights begin to flicker. When the 10dB above that LED became active, I was over the scale limit on the 140dB range and ceiling tiles were starting to fall.
I remember the old feed and before the utility company upgraded the poles to accommodate new houses being built across from me. Line voltage used to be 118V and that would sag to 96V with just my Hafler 500s back before I got the big QSC industrial amplifiers. The QSCs are capable of pulling 92A each when operating at full power into 2 ohm loads. And the fluorescent lighting would extinguish on bass peaks, due to the voltage sag.
The new service is 123.3V at 200A. Now there is little voltage sag, and the system has effortless concussion capabilities. I didn't expect to notice much difference at moderate levels, but it's there, too. With more voltage, the reservoir capacitors operate at higher voltages, so the rails are higher potential, and since ExI=P, the power increase is significant, especially when current is being drawn and the line isn't sagging ridiculously like it did before.
It was a painful $7000.68 expense to upgrade, and I had to put off repairing the roof and probably won't make this years's December property tax payment unless my amp repair business suddenly goes balls to the wall with work (not likely during the holiday quarter), but at least now I don't have to worry about problems with the electric line going up in a giant arc flash, and the stereo system got a no additional cost upgrade in the form of the power it was starved for.