I just found your question searching for an alternate issue. You have probably settled your system by now, but I wanted to pass on some of the things I experienced moving my 2.3's to a more smooth sound. I love their passion and texture, but my ears find them painful with conventional ss equipment. I just finished a new system upgrade and moved to tube pre and amp. I chose the Blue Circle Despina pre and switched the 6922 tubes from Electro Harmonix to the 1964 NOS Amperex 7308 PQ, white label, made in Holland. An excellent match with the Thiels. I found the Electro Harmonix tube very cool and harsh in mid to highs - bad match for Thiels to my taste.
As to amps, I am driving mine at more than adequate volumes with a prototype 35W tube amp by a local designer (Gordan Maughan). I never thought it would drive them, but ample headroom and power. So I learned that all amps are not designed the same. I had previously auditioned a pair of VTL signature 500W monoblocks in my home. Beautiful sound but expensive and high maintenance. The 125W VTL monoblocks clipped badly against the 2.3's at moderate volume. I am not an amp design expert at all, but if I had to go back to audio 'salon' offerings I would check out the VAC amps as I believe they can offer lots of bang at lower power. I did talk to them and found them very knowledgeable about lower impedance speaker driving. See the audiogon listing that references Thiel using 100W VAC in their showroom.
I have auditioned a lot of solid state amps against the Thiel's in my home. I will just mention a few. I found the Rowland Concentra II and the Musical Fidelity A308 way too etched and extended in the high frequencies for my comfort with the Thiels. I just had the Blue Circle BC26 ss amp in and it had ample power with a smooth sound.