That phase issue is a big problem when recording drums in our rehearsal place. Sometimes it's pretty straightforward, i.e. when recording snare with two mikes, one on top one on bottom - you just flip the phase 180 in the mixer and it's perfect - but then what about the kickdrum mic that's real close to snare bottom already?

The problem would be much easier to solve if we could listen to the mics while placing them in a separate room, but as we can't, it's anybody's guess when placing the mikes, whether they will be badly out of phase or not. Plus the lack of proper stands for all the mics...