Another factor with larger rooms is sheer SPL; with a larger room there is a tendancy to turn things up louder, and that can have a huge effect on the perception of the bass content. To understand why just look at the Fletcher-Munson response curves and see what happens to the response of the human ear/brain to bass at different SPLs. Music program played at 100dB will sound completely different than the same material at 80dB, sounding far stronger in both the bass and the treble even though the relative frequency response is no different; what is different how your auditory system responds to sound at differing levels.