Hi hammer,
kcarlile is correct. Although in theory, putting the M3s on their sides should screw up the dispersion patterns and cause degradation of stereo imaging, in fact, it seems to have remarkably few audible effects. I did a bunch of experiments with the M22s vertically and then on their sides, and I was hard-pressed to hear significant differences. On the other hand, at the time I was listening for coloration and tonal degradation rather than problems with imaging.
There seem to be some consensus that the tweeters should be on the inner side closest to the center line between the speakers.
Regards,
Alan
