Custom footswitch help

[Cronald]

Hi there, a few months back, I put together a footswitch for my H&K Tubemeister 18.

As it sits right now, it's a two button footswitch that toggles between the clean/OD channels, as well as turns the lead boost on and off. In addition, I've added a footswitchable loop tied to the channel selector. In essence, you can have a pedal on for one channel, and off for the other. It can be used to, say have the standard, "hi-fi" like OD, and then switch over to the clean channel with a fuzz pedal for something a little more dirty. I've installed a slider switch so you can select which channel the loop is active for, so you could alternatively use a tube screamer on the OD channel, but retain the amp's normal clean channel without hitting multiple buttons at once.

I'd like to revise it to have fewer cables running back and forth between the footswitch and amp, as well as tweak it and add functionality.

Right now, there's two stereo 1/4" jacks. One goes straight to the footswitch jack on the amp, and the other goes to a stereo to mono splitter cable, which can then be connected to other pedals that are not meant to be switched on and off by the footswitch, and then of course, back to the fx loop. Currently, I've got it set up as follows

Amp FX send > tip of stereo cable > footswitch > fuzz pedal > ring of stereo cable > reverb pedal > amp FX return

I keep my reverb pedal ontop of the amp to simplify things, and I keep reverb on all the time anyway, so no big deal.

What I'd like to do is ditch the need to run two stereo cables, and instead run an 8 pin MIDI cable between the footswitch and a breakout box that will be affixed to the back of the amp. The breakout box will contain connections for the footswitch, send and return jacks on the amp, as well as a 9v DC jack. All of those signals will then be run through the MIDI cable, which will connect directly to the footswitch. The footswitch will have two sets of FX loops. One will retain its connection with the channel selector, and the other will be before/after the footswitch*. I'll add several DC jacks to the footswitch too so I can run power to pedals (I currently have a 9v transformer connected directly to the mains inside the amp. Its output is on the back of the chassis in the form of one of those jacks.)

At the moment, if I try to run a tube screamer on the OD channel, I get a bit of leakage to the clean channel if the pedal is left on. How can that be alleviated? Resistor across the leads? Capacitor? or is it simply as a result of my wonky stereo cable setup? As for that asterisk up there, I'd like to add a switch that dictates whether the the non switchable loop sits before or after the switchable loop. Is that going to be possible? H&K amps require a slight tweak to the wiring as compared to the standard 2 button footswitch wiring (IE, Marshall) I'd like to add yet another switch to toggle between standard and H&K wiring... I guess you can say I have a thing for switches huh? Would using non isolated metal DC jacks present a problem? Should I stick to isolated plastic jacks? I'd like to make this as robust as possible.

Sincere apologies for the incredibly long post and thanks for any help! I'd just go for it and build it as per usual but I don't want to order a ton of parts only to find out I can't use half of them. I'd also like to avoid spending as much time as possible rewiring it... That's exactly what I did the first time around! Solder, test, tear apart, solder again, repeat