Alright, so I love these amps, but the one thing that's always bothered me about them is the noise/hum from the fx loop. I've read similar complaints online from several other people, so here's what i did to eliminate the hum... 1. I put a 12au7 tube in V6, which is for the fx loop. This alone got rid of most of the hum. It's a much lower gain tube, which makes sense as to why it quiets things down. 2. The cable that goes into the return of the fx loop needs to be elevated or out of the way somehow, because it causes interference, which also creates that hum. You'll have to get creative on how to elevate it. Well, that's really it. I'm not an amp tech by any stretch if the imagination, so I have no idea if putting a lower gain tube in v6 will cause any harm to the amp (i doubt it though, and i actually got the idea from an amp tech), so don't come to me if your amp blows up, lol! All i can say is that by doing this, the annoying hum is gone, and the fx loop sounds so much better. My pedals sound cleaner, and clearer. My Bigsky would make a loud hissing sound when cranking the mix knob, but it's so much quieter now, and the detail for my fx pedals is much more apparent (it's more like running pedals in front if the amp now). Anyways, i hope this helps!