Hello Nick,
nickrose:
If you have the patience, be so kind as to try TRS cables and let us know how you get on.
I use TRS-TRS cables for expression pedals and a Y-cable (TRS–>2xTS) for switches. This is exactly the same hardware that works well with my GTR 4000.
If I assign only one pedal or only one switch, then the pedal/switch behaves almost as expected regardless of what function the pedal/switch is assigned to ("almost" because there are some further issues of minor importance at the moment).
But if I assign a second pedal or switch to whatever function/parameter, then both pedals/switches behave unpredictable. Their values are both freaking around (producing audible clicks), they become dependent from each other (pressing switch/pedal 1 will generate significant artefacts at the parameter/function assigned to switch/pedal 2 and vice versa). This freaking behaviour persists even if all hardware (pedals/switches) is removed from the H8000FW and only the assignments are there.
If I assign a third element (pedal or switch), then it's getting really crazy, absolutely uncontrollable. If you only could see that…
I still believe in a SW and not HW issue because of the unpredictability. I can consistently duplicate "crazy" behavior, but I can not duplicate a certain behavior.
Thanks,
Thomas
