small, just as a matter of general information I was fortunate to run across in the forum here, you can tune the m60s by stuffing an average sized cat into each port. This of course doesn't give you a specific answer relative to depth, but it should assist you in a rough approximation of the volume capacity of each port.
My technical skills are wanting and I am unable to articulate this answer in a more numerical manner, so I am hopeful Bren will be able to step in and take this to it's next level. I have been reading his posts with some interest and he has displayed a technical expertise that, I believe, we should all strive to emulate.
