Thanks. Very good answers... and a real nice system as well !!
Maybe I'm missing something, but...
I think you're saying that you normally leave the M80s set to Large when playing DVDs, right ? Without the firmware upgrade to give you the Enhanced Bass option, any speaker set to Large does not send any signal to the subwoofer. This is true for all inputs and modes, not just stereo.
With the M80s set to Large, the only bass you are getting through the sub is (1) the LFE channel, (2) low notes from the center channel, (3) low notes from the surrounds. This would give you exactly the results you are hearing... relatively little output from the sub except on the louder events when the soundtrack might punch some energy out to the LFE and surround channels. A lot of the "interesting" bass seems to go only/mostly to the mains.
If you have mains set to Large AND sub turned on, the T163 seems to send low notes from center and surround to both sub and mains, while the LFE channel only goes to the sub.
Can you try something ? Set all your speakers including the M80s to Small, set crossover to 80 or 100 Hz (suggest 100 for now), and then do a quick calibration on the system to make sure the levels are right. If the sub levels need to be set very high or very low then adjust the sub gain so that you can have all the speakers fairly close to 0dB. If you still see the same problem in this configuration then you might have a sub problem, but my guess is that things will work OK.
When you get the Enhanced Bass support with the firmware upgrade THEN you can start playing with running M80s in Large
