I believe the bass response is created by the 2 ports on the bottom of the unit. As long as it has a wall to work with they are probably alright. Not sure how the angle affects it though.

Yeah, given the way I have them mounted, should the crossover still be 80hz?

See this thread: http://www.axiomaudio.com/boards/ubbthreads.php/topics/393058/1

You ask if the crossover should "still" be at 80Hz. This implies that a change was made since the measurement indicated that 60Hz was acceptable. If the mounting which you've discussed took place after that calibration, then yes, another Audyssey calibration should be made, since the amount of bass reinforcement from the room surfaces may now be different. Possibly something higher than 80Hz may be appropriate.

VoR,

You can try 80 Hz or 100 Hz and see if you can hear any difference. Honestly, given the rather minor contributions of Height speakers to the ambient soundfield (compared to the very substantial ambient field generated by your left and right surround speakers), I'd be surprised if you could detect any difference at all between 80 and 100 Hz crossover frequencies.

Regards,
Alan

I detect a difference between 80hz and 90hz. At 80hz, although the front sound-stage is a little more seamless, it has a little bit of a muddy sound in the heights in the low freq. range. When I switched it to 90hz on my Denon 4311, although I lost a little bit of the seamlessness, it produced a much cleaner sound. So, I'll probably stick with 90hz.

Plus, my QS8 surrounds are set at 90hz (as set by Audyssey) so they match those perfectly now.