Well, after lots of time and money, I finally have my big pedalboard set up for stereo. Yay! Sounds amazing, except for one thing. I have an American Loopers bypass looper, a pretty big one, has 6 mono loops and 4 stereo. Now, for a reason I can't figure out, whatever pedal is on loop 10 (the last loop), there's a constant and obnoxious hum. I sent it back to American Loopers, he couldn't reproduce the problem, even sent me a video showing how he couldn't reproduce it. He tried it in stereo, as well as mono, as well as each side. I've tried to troubleshoot, here's what I've done, all of which made no difference. I don't even think it's the power in my place, as I had the problem when I brought the board somewhere else. Put other pedals in that slot Doesn't seem to matter if other loops are engaged, or not Tried it just mono Tried another new cable Put the pedal on it in another slot (didn't make noise on that slot, so it's obv. not the pedal). Powered it from one iso power supply. Powered it from another iso power supply Powered it with its own power, just plugged in The looper goes back to an Empress stereo buffer, to a DI, then XLR's out to my PA. Tried the ground lift on the DI. Bypassed the buffer and DI. I'm kind of at my wit's end, here. The looper is so quiet, except for that last loop, and I need that last loop, too. What could this possibly be? Out of options, here.