I have auditioned the X series and I also posted a dicussion question several months ago, asking if someone could explain the differences between the Aleph Series and X series sonic differences. Someone from Pass posted a nice follow-up. You may want to go back and look it up. I have listned to Krell, YBA, Mark Lev, and Jeff Rowland. And I personally believe you cannot go wrong with Pass Equipment. The Pass beat Krell hands Down, the YBA, Mark and Rowland all had there + and -, but when you factor in the looks of a Big X600 and that Ery Blue meter shining in front of you that was enough for me. There is a shop in Phoenix AZ, called Speaker Ect. 2 really nice guy run it. Give them a call and I'm sure they will anwser any question you have.