This thread just saved me $58 with shipping.
I have 4 hum destroyers, the Behringer HD400... A while back, I was hunting down a noise problem that I create with my rig as a result of a nasty 8 or 10-cable method setup with my Stomp and a couple of M13s and my Powercab. (I like having all the footswitches available.) Oh, but simply plugging in a USB cable to my Stomp and computer caused a real sonovovich of a hum to show up again.
Well, I had forgotten why I bought so many hum destroyers until today. I couldn't figure it out again. I blamed it on the USB. And sure, it is the USB. But the answer: a hum destroyer right before my Powercab, in the audio path. No USB isolator necessary. If isolating the USB doesn't work, just skip it. Use another hum destroyer, HD400.
Thanks to you all for your comments.
