Hi Tim
> Thus I would suggest two things: operating it with the LED not quite
> lit; and be guided by your ears (unless anyone else has anything to
> offer...)
I don't own the Fq Shifter but once a friend borrowed me another diy
FqShifter box, that worked basically on the same circuits. For useful
results with a guitar or saxophone we had to preprocess the signal with a
heavy compressor (ration 1:20) and a noisegate. Your experience confirms
this.
Though the core chip of the module quits its work due to too high input
signal voltages, I do not think that any damage might happen within the
A-100, because Doepfer input circuitry usually uses limiting parts in
sensitiive modules.
Florian