Perhaps my question shows my ignorance in understanding the benefit of arbitrary stereo separation when performing with BIAB. Why is the sound better just because the guitar seems to come from the left or the trumpet from the right etc. If you are listening to a live band and you can see the lead guitar player standing on the left then perhaps it adds to the experience but when everything is generated electronically and the sound appears "out of nowhere" I cannot see the need for stereo separation. This is especially true when using a mono PA system.

Also when using BIAB at home through stereo speakers or phones I find the panning very distracting so usually get rid of it anyway.

BTW separation for a stereo piano played from a keyboard is different and is essential for a good quality piano sound but that isn't part of the BIAB style. I have my mixer piano input set permanently with left panned fully left and right panned fully right and keep the separation through stereo PAs.

Tony