Now, there too many unknowns to answer simply. Room size, MLP, sub placement, volume level, present and desired target responses, etc. You could make it a lot worse, or improve it somewhat. It is hard to do without some ability to measure; check out the REW thread and see if that is of interest. If not, you may be fine just letting your AVR handle them. You can always play around and see for yourself.
"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley