I completely agree with the comment about bass in hi-fi. Large drivers in speakers need a lot of both current and dI/dt to kick the unit into motion fast, and then brake it, with drums for example and so anything that limits either is really bad. I made sure that my power amplifier was on its own line directly into the consumer unit, not on a ring with anything else and tried to maximise the current delivery with thick copper cable whose length was kept to a minimum as best I could. I used to be a bit of a hi-fi nut when I was still well. My minuscule knowledge of electronics is largely confined to audio.
I’ll need to dig for the papers g3uiss mentions. That means I’m still a sinner then, if gizmos between the networking equipment and the output of the UPS are verboten. I wonder why that might be?