Hey Herby, possible
but not likely, more likely the DJ thing may have damaged it, but who knows, could be neither ?
So if I understand correctly how you were running it, the right channel you used in front of the MP1 so you'd set that at -10 (as signal is instrument level at that point) and the left channel after the midiverb so you'd set that to +4 (as is now line level). If you were driving it too hard (left channel) you should have seen it on the input meter (or heard clipping).
In the DJ rig you'd set both channels to +4 and probably select stereo link (so the channels operate as a pair). DJ rigs are often pushed very hard (and often by people who don't really understand what they are doing (audio/PA wise)) to get the most volume from them (otherwise, why use a compressor in a DJ rig
, although using it as a peak limiter to protect the amp and speakers does make sense).