Opinions on Thiel CS2?

I own the 1994 CS 1.5s and can tell you they are outstanding considering the small cabinet size.
Never heard the CS 2s but i would suspect they are juste as good.
A high current amp is required for most Thiels.

joefama, got it right. Perhaps Thiels most reliable and easiest to drive model, with their smooth 6 Ohm nominal 5 Ohm minimum impedance. Perhaps the last of the Thiel models that really, really needed attention to the treble. Many used c-j tubes with this model in an effort to tame the treble, but I personally found the ported bass to be too wooly driven as such. A steal on the used market, but be prepared to spend a little on amplification. Not so much because of their a challenging load, but just because of their particular sonic qualities.

Buy 'em!  

My enthusiasm neglected to include mentioning that Thiel's Rob in the service department can give you advice and estimates on anything you might find needs replacement/refurbishing for the 2's.  That's comforting to know that the legacy models can be given an even longer life. 

I bought my Thiel CS2's in 1987 or 88 for $1500 the pair. Used them ever since. All above comments/observations are accuratee in some way or another.
I have always use solid state to run them, Bryston too bright, Hafler just right! Program material will also determine sound quality.
Agree tubes might work well with them as I may have heard them thru tubes on first audition. I didn't look at the amp. However, CS2 specs say amp power range starts at 40W. In a well dampened room the sound stage appears dead center. Hope you enjoy!