The X don't sound as good as XA.5s given that the XA.5 provides sufficient power, they are not both "similarly excellent". So, if 160 watts is enough power for your speakers, room, and loudness levels you listen at, I don't think there is much doubt as to which of your two options is preferable.
Pass X vs XA amps sound quality in class A range
If you are one of those lucky enough and has the means to upgrade from the X (or X.5) to the XA (or XA.5) Pass labs amps, is there enough of SQ differences in low power ranges, say between 5-25W, where they all perform in class A mode, supposedly. Thanks for any insight!