djwayne
I don't know but my recordings just sounded richer, maybe a little louder than before.
That's a placebo effect. Lots of things will impact your hearing, and unfortunately, a great deal of those things don't involve your ears. This is why audiophiles are a particularly cranky bunch. Null tests, and double-blind listening tests will piss off audiophiles to no end because once they get a "feeling" about how something sounds, it's near-impossible to convince them otherwise.
If you really want to be sure that X3D sounds better, roll back to X3C, or open up a mix in X2, then export it. Then export the same exact mix in X3D. Assuming you don't have any randomness going on in your signal path (like random noise in a tape sim for example, or a random modulation plugin), you should end up with identical mixes. To prove it, load both up on separate tracks in Sonar and flip the phase. You should be left with absolute silence. If there's some audio left over, then something is in fact different.