Any time we’re filtering and then summing two coherent signals, we need to be aware of any potential lurking phase demons.
Illustrating the harmonic structure (content and phase relationship) of a signal
Combine two equal level sources: Do we get +3 dB or +6 dB? The correct answer is yes. And there are even more possible outcomes as well.
Ultimately, you cannot completely avoid phase cancellation, you can only make sure it sounds as good as possible.
Overcoming feedback problems while keeping house and monitors in balance.
While a complete exploration of the two concepts would fill an entire book, let’s take a brief look at each concept, in a nutshell.