Hi everyone,
First post on this forum.
The only thing I have to add to this discussion is to remember that the signals produced by musical instruments are very complex and impossible to predict. As a result, you can can have two microphones that are not
exactly "perfectly" out of phase with each other.
Phase invert swaps the phase of the signal 180 degrees and the sound may not be substantially improved if they microphone capsules are not 180 degrees out of phase to begin with.
Something like
this is invaluable when using more than one microphone
Radial Phazer™ phase adjustment tool - introduction
Hope you find this helpful!