I use env filters in floop all the time. It probably won't be the death of your cabinet, because before it could get that loud the summing circuit in whatever your using for the floop will probably clip. Assuming that's how the floop pedal works.
Anyway, env filter in a floop will sound many different ways depending on what else you have with it and what the settings are, but here's my track, "Empty The Vats."
http://speakonion.swizcorp.com/audio...The%20Vats.mp3
That is a sub-octave, distortion, trem, and envelope filter in a floop and then into a delay. That's all it is. So, all the THUMPS are made by the down-sweep setting on the filter, and most of the screetches are from the up-sweep setting and the filter sweeps are me going from one to the other.