My mains are powered by a pair of XPA-1Ls. I just, as in yesterday, finished a complete overhaul of the layout of my A/V rack, putting the XPA-1Ls at the very top of the rack (due to heat output). I meticulously managed every single signal and power cable. It was an enormous task. Last night I was enjoying some 2-channel music, and noticed between tracks a very very soft static out of the left speaker. Are you kidding me???!!!! My first thought as to the cause was a splice point in each of the mains' speaker cable. But immediately afterwards I thought how extra careful I was with those splices, to avoid such issues.
My second thought as to the cause was the power cable transmitting unwanted energy. I had an unused PS Audio power cable (with very good shielding) that I used to replace the XPA-1Ls stock power cable, temporarily, to observe any potential change in what I heard No more static!!
I know that power cables can behave as antenna, picking up various unwanted energy/signals, with unwanted effects on equipment, especially when 13 items needing power are all bunched in a 6' rack. But this is the first time I've experienced this firsthand. Very happy to find the cause.