Hang in there Kley! I'm sure you'll figure it out. I could hear the little ghost note thingie in the first video this time. Great news is that it seems super reproducible for you. A couple of quick thoughts as I pass thru: 1) I don't think you need to worry about the tone stack/yellow stuff. It's all in phase but not strong signals, it's common for all the tone stack signal to intermingle without issue. 2) @Lynxtrap makes a good point about filtering/coupling, those UCC electrolytics are ample and brand new so I wouldn't expect problems, but just wanted to verify you are following the D-schematic exactly for the power supply as well as which nodes feed which triodes? The filter caps also decouple AC, if you were to start sharing power nodes across the wrong stages you are subjected to yucky interactions. 3) Are you reproducing this issue on the clean channel or OD ? 4) Are you using a speaker here? If so, the speaker could be the problem, I'd try to rule it out. Had this problem recently. 5) I'd roll preamp tubes before getting to far into rewiring. Not sure if you had done this yet but I know you mentioned it. 6) No nukes!! You'll get it.