Pre-amp suggestions for Thiel 2.4/Pass Labs XA30.5

Cal3713, I don't read that as Nelson Pass specifically recommending the XA30.5 over the rest of the comparably priced Pass line for the Thiel 2.4's, only as a recommendation below 20 Watts. Seems like a highly qualified recommendation for a speaker that's manufacturer recommends a minimum of 100 Watts. I will grant you that the XA30.5 does seem to behave more like a very high biased 100 Watt "double down" Class AB amp, than a 30 Watt limited pure Class A amp. Perhaps capable of 75 Watts of Class A power into 3 Ohms before sliding into another 225 Watts of Class B power into 3 Ohms? On the other hand, I'll hazard a guess that the X250.5 is probably biased in such a manner as to be able to produce about 18 Class A Watts into 3 Ohms before sliding into about 730 Class B Watts into 3 Ohms? If you have a smaller room and/or don't listen very loud, the XA30.5 could very well work very well for you.

Unsound: This doesn't really matter, and I don't know the true state of affairs because I haven't directly compared the XA30.5 to the X250.5, but if you take a look at the entire thread, you'll see that it is actually a recommendation, and that the thread owner A/Bs the two amps on his 2.4s and vastly prefers the XA30.5. And in my listening, I'm in class A about 90-95% of the time.

In any case, this thread hasn't really addressed my actual issue. Regardless of people's perceptions regarding powering the Thiels with a 30 watt amplifier, removing the Classe from the system and using my PS Audio PWD as a preamp allows me to hear significantly more detail from my source components... so some successful preamp pairing suggestions would still be useful.

By the way, thanks for the folks that did offer some pre-amp suggestions...

Cal3713...I would assume a used Pass XP-10 would be a good combination with your XA30.5 (check with folks at Reno Hifi who often have good used/demo inventory and I believe they allow 30-day in-home auditions). Other options to consider:

ARC LS-17: http://www.audiogon.com/cgi-bin/cls.pl?preatube&1328708163&/Audio-Research-LS-17-Tube-Prea. very detailed/resolving but still gives you smooth/continuous flow of music with 3D presentation

CJ Classic SE: http://www.audiogon.com/cgi-bin/cls.pl?preatube&1329081914&/conrad-johnson-Classic-SE-tube. Shoudl give you the CJ golden hue but with updated modern and highly resolved sound. SE version includes Teflon caps which take a very long time to burn in (>600hrs) but should deliver on resolution and spatiality in spades. This looks like a good deal for a brand new unit with full factory warranty.

Good luck.

Cal3713, went back and read the entire thread. I still don't see a direct recommendation from Nelson Pass for the XA30.5 for the Thiel CS 2.4's. The OP does seem to vastly prefer the XA30.5 to the X250.5, but with the caveat of not having to play loud in a large room. The thread also points out that the Thiel Cs 2.4's spend much of their time below 4 Ohms. Aparently others there have had similar conjecture as I had re: output Class bias.
...But enough of that. I think the a Pass pre would be just the ticket. What ever you choose, I'd suggest using a fully balanced pre.