Sounds like the neighbours banging on the door. They either want you to turn down or play requests ?
I haven’t ever heard a noise like that from my Powerhead but I remember the first time I heard a weird ticking on the playback of a recording. We tried to everything to locate the culprit but nothing we did made any difference. Then we noticed that it only happened when I put my hand on the guitar neck. It turned out it was the ticking of my watch being picked up by the guitar and amplified. That was 1995 and I still suffer from that problem to this day.
I have experienced the same phenomena when wearing a soundbrenner pulse on my fingering hands wrist :p