I'm sure Thiels can sound good with tubes- I'd love to hear that combo some time. But I bet they have to be some massive tube amps to get the full range like I enjoy. I found that the Thiels work much better with amps that have plenty of power and current. i.e. when the amp power rating doubles for each halving of impedence down to 1 ohm then it is capable of driving the Thiels.
I started out with a lesser amp and my new Thiels at the time just didn't quite do it for me. So, years back I took home the PL X350 from a dealer for an audition and that was it. I have been enjoying that amp with my CS6's ever since.
Of course the X350 was not cheap either. But it has so much power and current it can make just about any speaker stand up and salute. :)