>The little JBL *really* messes with the monitor, just now testing moving it around near the monitor, for whatever reason. It may be that nearby stereo components and PC speakers are compounding the magnetic effect or something...but I was kidding previously about a big imbalance problem, moving the rear JBL about a foot away from the monitor solves the problem well enough.

It's not surprising, since it wasn't specifically designed for use in the PC environment - moving it a few inches away may well cure the problem - magnetic field strength decreases as a function of distance^2.