Your room is part of your system, and it's usually the most broken part. Bass especially is wrecked by room modes — peaks and nulls that can swing the response by 15dB or more. Room correction uses a measurement microphone to map what's actually arriving at your seat, then applies digital EQ (and time alignment) to flatten the worst of it.
The good systems — Dirac Live, Trinnov, and increasingly capable versions of Audyssey — make a genuine, sometimes startling improvement, particularly in the bass. But correction works best below the transition frequency (roughly 300Hz); above that, physical acoustic treatment usually beats EQ. The best results come from treating the room first, then correcting what's left.