Integrated Amp for Thiel 2.3 s ?

I agree with your assessment of the combination you are currently using. Classe CAP150 or CAP151 (newer version of the 150, virtually the same) is a much warmer integrated vs. the Krell. I've heard both with the Thiel 2.3s and the Classe is much better....smoother, more refined highs with good bass control.

I have had the same problem with my Thiel 2.3s and yes a tube preamp does go a long way to control the bright top end of the Thiels. I am currently using a Krell KST 100, VTL 2.5 Preamp with MIT MH750 cables with excellent results. So before you replace your Amp try using MIT MH 750 speaker cables. Will the cable change be enough? Maybe, but give it a try. You can get them at Audio Advisor at 50% off and it they don't work return them within 30 days for a refund, no questions asked. Just be sure to break in the cables before making a final judgement. One final thought. If you do replace the Amp be careful what you use and try if possible to audition it in your system. Thiel 2.3 are a real pain to match correctly. I tried using a BAT VK 200 and BAT 3i and thought this combo was the ticket, the sound was way to bright. A terrible match. Also tried the Aragon 8008st, much better but my current combo seems to work best. The Thiels do sound very good when matched correctly, its just very hard and at times fustrating to get it right.

Thanks GJRAD.
My cables are now the Monster M2.2 which I have been told is a "warm" cable. Do you really think the MIT 750 will be that much different? Also I'm thinking of getting the Arcam cd23 instead of the Rega Planet which I now have. I'm told that CD player might do the trick. With a great recording my system sounds terrific----BUT I have way too many CD's that just sound too harsh or bright.

The MITs will definitely soften the high end and I believe its worth a try before changing the amp. My son is using an Aragon 8008st and AR LS3 preamp with Thiel 2.2s also went to the MIT MH 750s with good results (took that bright edge right off), although the 2.2 are not nearly as bright as the 2.3s and IMHO a better sounding speaker. A tube preamp will make the most difference, the MITs just completes the package. I have not changed CD players, currently using a Micromega stage 2 and 6 but of the ones I tried none made much of a difference to control the brightness. Your other option is to sell the Thiels and replace them with speakera that are warmer. I listen mostly to Jazz, Accoustic, and some Rock, the Thiels if not matched right will not even come close to what certain instruments should sound like. Example listen to Ken Navarro, with the Thiels you would run from the room in pain. Get it right and he is there with you. Hope this helps.

The Plinius 8200 will do a decent job with the 2.3s but will not entirely remove the slightly whitened nature of the sound of these speakers. I have spent quite some time with the 2.3s, including with tubes, and believe they are a struggle to make them musical with a wide range of CDs. As suggested above, you may be better to try some other speakers.