"If the choice is between the X350.5 (MSRP $11K) and the XA100.5 (MSRP $16K), then what would you say?"
XA100.5. But don't rule out the 60.5 or even the 30.5 especially if you don't play your music that loud and I'm guessing you don't with the CLS. Electrostatics are capable of such great microdynamics, an XA.5 should be a great match for them.
For a preamp, Pass's XP-10 or 20 would be a nice match and if you favor tube pres, Conrad Johnson is my favorite. As I'm typing this in my office right now, I'm listening to a CJ CT-5 driving an XA30.5. I've had no desire to change this combo in my office.
XA100.5. But don't rule out the 60.5 or even the 30.5 especially if you don't play your music that loud and I'm guessing you don't with the CLS. Electrostatics are capable of such great microdynamics, an XA.5 should be a great match for them.
For a preamp, Pass's XP-10 or 20 would be a nice match and if you favor tube pres, Conrad Johnson is my favorite. As I'm typing this in my office right now, I'm listening to a CJ CT-5 driving an XA30.5. I've had no desire to change this combo in my office.