What's wrong with Thiel?

All I can say is that I'm a long time Thiel owner and all the advise above is right on! Don't be afraid to call Thiel, their customer service is second to none.

SS: good response!
What I'd like to add is that Thiel has always taken the flat, neutral spectral response school of crossover design and tweeter padding, so his speakers sound lean and too-bright in most systems. Adding a flat, therefore bright-sounding Harm Tech or Nordost to a Thiel-based system is not to my thinking a wise choice UNLESS your upstream CDP is VERY warm and/or your room is VERY damped.
A high-current, ballsy amp is required, along with sufficient listening distance for proper coherence, as stated above. But if you start with a flat cable with your leannish 2.3 you may find that engineering a slightly-tilted
spectral response (what most of us prefer) to be an uphill (no pun intended!) battle.
So make sure you sit far enough away, without pushing the 2.3 back, and therefore foreshortening the soundstage (ouch!), dampen the floor, sidewalls, and possibly the ceiling (least important), and then tweak your front end and its IC for final optimization.
FWIW Thiel's latest 1.6, although lacking in the bottom octave, and limited in SPLs, is DECIDELY warmer in signature to its brethren the 2.3, 3.6, CS6, etc.
Interesting. Is Jim relaxing a bit? Ha.

I have had a pair of Thiel CS2.3's for about 18 months. The Thiel sound is fast, detailed and transparent and the CS2.3's have it in spades. I have auditioned many speakers up to and including JmLab Utopia's and Revel Salons. I prefer the CS2.3's to all of them and I won't apologize for it.

There are some people who think that Thiels are bright. For those people there are proacs or any other speaker with a blanket thrown over the tweeter and midrange. Each to his own. Let each person vote their preference with their own money.

Back to the Thiels and the CS2.3's in particular. As mentioned previously they are designed to be listened to at least 9-10 feet from the speaker so that the drivers can properly integrate. Thiel mentions this in their documentation. They require good amplification, preferably an amp that can double down to 2 ohms. A pass x250 would work nicely. The x150 will probably also work well as long as you listen at reasonable levels, <100db. BTW, I was bothered by the fact that the Stereophile review on the CS2.3 was conducted with the VAC 70/70 tube amp. IMHO there is no way the reviewer could get the best out of the Thiels with this amp. However Thiel has since used VAC amplifiers with their equipment at CES so what do I know.

Because of their resolving and detailed character the Thiels will be very sensitive to placement and to changes in cables. However I think cables are a blunt instrument when you are trying to tune a system. I recommend a TacT RCS so you can have the maximum amount of control and flexibility in tuning your system.

All good points above. Matching amplifiers is important not just for Thiels if you want to approach perfection. A speaker that works well with a lot of amplifiers is less likely to be great with any one amplifier. Just like Pavarotti is great at opera, he is not very good with other music styles. Where as the girl that won the America idol competition can sing many styles well, but she is unlikely to be great at any one style.

So think in terms of a whole system, not individual components.

At a local dealer while the 2.3 was hooked up, somebody did make a comment that it was bright and nasty. When I looked at the amp and speaker wire hooked up to it, I realized that the sound was purely the sound of the amp and wire. Big emphasis an purely. I thought they were awesome. I bet finding hearing what a speaker cable sounds like would be easy with them.
With those, the big question is, what does the amp sound like.