Good luck proving the audibility of the effect. Other coupling factors (besides Lorentz force) tend to cause issues running parallel wires, but chances are unless you are doing live sound with a 100' snake running power, speaker, and mic cables in the same bundle, you won't hear anything.[/quote]
Even then it is a non issue.
For decades manufacturers have been making audio snake cables with mic and speakers in the same jacket. And then in most cases an AC power cable is either run right beside it or taped to the snake.
I have yet to run into a case that had any issues.
And when you look at concert sound you have mics and AC power run side by side for several hundred feet (300ish) with no issues. Of course there are no speaker levels in parallel with mics in large setups-except on stage.
I was in the PA rental market for about 25 years and never had an issue with mic cables/speaker cables/AC cables interfering with each other-at least that I am aware of.
Sure it is a good idea to separate them and have them cross at 90°, but it does not make any audible difference (that i am aware of anyway).
I could see a problem however with unbalanced cables and AC cables since the common mode rejection is not there as with balanced cables. But then shorter cable lengths would probably make a bigger difference.