I am mostly successfully using the iRig Pre + GarageBand iOS to output my vocal mic into a Bose L1 Model 2, using the Bose 1/4 inch analog input. I say mostly because for the majority of my 2 hour gig yesterday it worked great. But about 3 or 4 times the vocal would quickly get very hot, as if a cable that was partially plugged in had made a cleaner connection, but then would return to the normal output within a second or two. I worked with it for a while afterwards and also back home, and can't manually get any such glitch to occur, using the same cables, jiggling them, changing the controls in GarageBAnd, etc. (I'm using the GarageBand Audio Recorder instrument, using Voice as the option, which gives me controls for compression, tone, and reverb amount, etc.)
Anyone seeing anything similar? Anyone using some other iOS software/hardward combination for a similar need?