I haven't tried all combinations so far, but it definitely works!!!
I owe you one (hoffentlich bist Du nicht so weit weg und das Bier schmeckt dort
).
What I've noticed is that (yes, I can see in the code that you specified a note-on message) it switches twice, on note-on and note-off, but I can filter that out, no problem.
WOW - the first step is solved, so amazing! Now on to the weird Arduino controls and possibly the intranet audio streamcast
Tausend Dank nochmal, Wahnsinn!