Upgrading CP35 Preamp, Sugestions?

I'm looking for a better preamp to go with a Classe CA100
and Sonus Faber GP speakers. I have a Classe CP35 now.
I was thinking about getting a used CP-45 or CP-50..
Has anyone tried the CP45 or CP50 ?? Are they a lot better
than the CP35??
I went from a cap 80 integrated to seperates CA101\CP-50.
It was refreshing. Try to get your hands on that cp-60 with the outboard power supply. Never tried one but it sure sounds cool.
I went from a Classe Model 30 to a Classe DR-6. I then tried a ARC LS-15 tube pre. The LS-15 performed the best with my CA-100 and CA-400 amps. A lot of folks suggested a tube pre and they were right. Good luck!
The DR6 is much like a CP60 ??
Did the DR6 sound worlds better than the CP30?
How would you describe the sonic change??

Tom, the jump to the DR-6 was a big improvemnt over the 30. Better soundstage, improved presentation. But my DR-6 was an older model that did not have balanced outs or a remote. I borrowed the LS-15 from a local dealer to try out. The tube pre was an even greater improvement. But I have to mention that the DR-6 and LS-15 are a decade apart. The CP-60 is Classe's current top of the line. If at all possible, audition some different pre-amps to see what works best in your system. Good luck!
Classe DR-6 is life time warranty.Please check it with classe to make sure.