In the spirit of learning I'm "building" a single input layout for a 5E8a. It seems to me that that unless you have a Y cable you can't just access both sides of V1 or V2 but you could jumper channels. That would be the same as using both sides of one tube, right? Im wondering if the two 5U4's have an impact on the sound. Could we just replace these with one 5AR and accomplish the same thing? I'd imagine those two 5U4s sound similar to just using a solid state rectifier. Any and all info is welcome! I've got a dead HRD that I would love to put this in. I already have a 5F6a and an AB165 (converted the normal channel to an AA864) so I figured this would be a fun circuit to add to the mix. conversion kit for Bassman head if interested: https://vintagefenderamprepair.com/products/ab165-to-aa864-plus-tweed-preamp-for-blackface-ab165 Current layout: Im assuming the extra 100k's at the input were mixing resistors so I removed them. The goal is no shift in tone but simplified. What do you guys think?