here is a quote from Chris (Audyssey) Look at the last part, this is a answer to a gentleman that was asking about his sub seeming lower than normal after room correction.
1. Your couch is close to the back wall and the bass buildup there is telling the measurements to cut more than needed. Moving the mic at least 18" from the wall usually fixes that even ...if it's not exactly where your head will be.
2. Your couch is in a deep null (usually near the center of the room). MultEQ limits how much boost it applies because putting energy into deep nulls is not effective.
3. You have a personal preference for higher bass levels than the film reference that Audyssey sets. This is easy to fix: just turn it up for your own preference. The MutlEQ response is not affected.
4. You have been listening for a long time to an uncorrected sub with a big peak at one frequency. Once that's smoothed out some people report "missing the punch", but in fact they are now able to hear content above and below that peak that was previously masked. Finally, I hope that none of your speakers are incorrectly set to Full Range. That's a sure way to kill the bass going to the sub.