Hi, I would suggest you go for Mark Levinson simply because X1 is more 'designed' to gear with its corresponding X-series power amp. ML380 should be more flexible in terms of compatibility. I have heard X1 running with X350 and the sound is great. Likewise, I used 38S for several years and find that it is also a very reliable piece of equipment. If you can raise your budget a little bit, I strongly recommend you to go for Ayre K1-x which I find is superb among all other preamps of this price range. Ayre K3 would be cheaper but still coult 'win' ML380 I believe.
Good luck.
Wong
Good luck.
Wong