The higher up Audyssey's MultEQ
chain you go, the more filters / better resolution you get to your auto EQ-ing:
____________________________________________Filter resolution (satellites)
2EQ: x | MultEQ: 2x | MultEQXT: 16x | MultEQ XT32: 512xFilter resolution (subwoofer)
2EQ: n/a | MultEQ: 128x | MultEQXT: 128x | MultEQ XT32: 512xNumber of Measurement Positions
2EQ: 3 | MultEQ: 6 | MultEQXT: 8 | MultEQ XT32: 8
Basic MultEQ is good. MultEQ XT - which is found on the X2000 and X3000 - is better. The version on the X4000 is their top-tier MultEQ XT32 which features:
- more filters for both subs and speakers; and
- Sub EQ HT, which helps with calibrating dual subs.
If either the X2000 or X3000 has everything you want/need on it, and if you don't have or don't intend on getting dual subs, you may not find it worth your while (and money) to purchase the X4000 instead.