Sorry if this posts twice but my first attempt did not propagate.
I’m having two seperate MIDI issues:
#1) When my Sub37 is connected to my Kurzweil MicroPiano module it will occasionally drop the connection which can only be fixed if I reboot the Kurzweil module. It happens every 30 minutes or so.
#2) also when connected to my Kurzweil module there is a faint motorized clicking noise that is heard through the output of Kurzweil module when I twist any nob on the Sub37 (except the headphone volume knob).
Hooked my Sub37 (1.0.13) to Kurzweil Micropiano, played it a bit, left it switched on for the night, played it again, tried all knobs – everything works as expected, don’t see the nasty thing you describe. I’d try changing MIDI cable and swapping power outlets.
dunno about #1, but #2 sounds like some species of “ground loop” issue. These are notorious in modern studios because everybody is using computers and devices with USB, and there become many paths to electrical ground, which can propagate weird noises throughout your system.