Did you recalibrate your speakers (using SPL meter)? The difference in loudness could make it that the M50s are now contributing more to the sound than your central channel. Also, if it has a better tonal balance with your center than your previous speakers, than it will create a much more seemless soundstage that will make the overall experience feel more natural.

E = MC2 = ((2M80 + VP180 + 4QS8)/(EP800 + EP500))^(ADA1500 x D2v)