Personally I use MT mode for backing tracks as I have individual instruments/tracks per each output at back of unit and
can fine tune overall mix at console.. I was going to use ST mode for background music between sets, but actually used other devices so far.. (LP-16 only supports wav’s so you would have to converts mp3/flacs to wav’s for that purpose, plus there is a bug with pop/click going to PA when changing modes.. -its going to be fixed at next update apparently)
Anyway, if you have created stereo playlist it will only be accessible in ST mode… similarly multitrack playlist in MT mode.
It depends in what application you use LP-16, but for me MT is what this device is all about..
It allows you send multi track backing tracks to console on individual channels and play midi file in sync same time.
I guess if you have simple mono backing track and just wanna use left channel for track and right channel for click (as example) then ST mode would be also suitable..