Weird things happening with my audio levels (hardware issue)

Since i put my setup back together (which consists of various hardware connected through a mixing desk), i'm experiencing strange behaviour in audio levels.

Let's say i play a sequence on the MPC60 and there is also a master keyboard and synth connected through MPC60 via midi, both the MPC and the synths audio are connected directly to the mixing desk. Now comes the issue: After a random short time... maybe after 5, 10, 15 minutes... the audio level of one piece of gear, or both, drops SIGNIFICANTLY... to a level so low you have to turn up the gain of the mixing desk to the max and raise fader to max to hear it at a normal level again. WTF?

This can be solved only by turning off the gear (MPC, synth) and turning it back on, then the audio level is normal again.

What's going on here?

Aight... i feel incredibly stupid...

I placed the synth on top of the master keyboard and the underside made slight contact with some sliders of the keyboard that control the volume of whatever is connected via midi. Everytime the synth touched the sliders a little (sliders were in the 0 volume position), it sent a midi command to the synth and/or MPC, basically muting them...

Ahhhrrrgg... almost went crazy trying to figure out what was the problem! Haha!

nice story
You might feel a bit stupid but IMO this is easier to take than to know that your gear have a serious problem and probably have to be send to repair.

peace