There has been some good advice in the above answers. It really depends if you want to spend the extra money or not and if your system is revealing enough to hear the difference between the two preamps. I have heard both your current and X20 but in different systems and it does appear the Pass has made the improvements that Peterayers mentions. Both preamps are extremely good. I will also mention that I upgraded from a very respectable CJ preamp to the Joule Electra 300ME and cannot believe how much more revealing and musical the JE is. The best upgrade I have made in over 30 years however it did cost alot. If you are dying to spend the money than get the X20 but both preamps are very good.
Pass X1??
I am using a Pass X1/X250 combo with nice results but am wondering if the x1 is one of those preamps to hang onto or is it so far obsolete that it could be easily beaten with a less expensive new preamp. My X1 sounds fine but have there been advances in preamps that make the X1 obsolete or is it a piece to hang onto for a long time. Mine is sounding good but as it is now the oldest component in my system I thought I'd ask. I recently got new digital which is indescribably better than I was used to and the digital I was used to was pretty good. I'm thinking the x1 may be a keeper because of it's simplistic design. I think if something goes wrong with the X1 that it will come across as obvious and not just degraded sound. I would consider the XP-10 but it does not have a tape out which is essential for my headamp. The X20 is simply far beyond reality due to price point. I guess my question more to the point is that if I sell my X1 for $2000 then what would far better it at the $2000 price point? I'm still thinking the X1 may be a keeper. It will require replaced chips as they are bound to go throughout the years but this is normal.