i went threw a bunch of pre's a while back, trying to determine which was the best fit for my system. agree with Tzh21y here. the X1 was the most neutral and added/took away nothing from the music. did not try anything from Wyred4sound but bel canto, krell, and a few others were in the mix. was very undecided until the X1 got plugged in. slam dunk for me here. aside from the rather lame remote control functions....i'm very happy with the choice.
if you have a good source and want to hear every bit of it... the X1 is fantastic imho.
btw....although i didn't compare the two, i've read the newer X1's with the full size power supply are "better" then the older versions with the smaller/black box power supply.
cheers
Lev