Thiel CS3.6

If the amp is comfortable at 2 ohms and the room is not too large, it should work fine. The Thiels crave current drive, not necessarily high wattage. If they don't get the current they need, they will sound bright and thin. Also, you should have 3 feet or more open to the sides and shouldn't sit closer than 8 feet from them.
If you give them those things, they are a delight, and one of the biggest bargains in used gear.

I have owned a pair of 3.6 since I bought them new in 1995.

IMO, they need a beefy SS amp to get them going. When I originally drove them with a Hafler 550 (255wpc) amp, I could not make them sing. Don't get me wrong, the sound was nice, but if you want them to sound their best, a powerful amp is a must.

Newbee, you should have heard those Thiels with a bigger Threshold! What tube pre did you use with the Threshold/Thiels?

Unsound, I used (and still do) an ARC SP10II. It was revelatory in its hey day. I wasn't so wild about the matching D115II though. Phono stage is still pretty good. And if I ever find some mint SA 1's I'll buy them just for the nostalgia effect if nothing else. :-)

BTW, I'm assuming you are familiar with Thresholds 'optical bias' which was introduced after the initial production of the SA series. Did you find it added to the sound, quality wise? I never heard it but the feedback I got was that it sort of brighten them up a bit.

I hope the OP won't mind this?
Newbee, I haven't compared non-optical bias with an optical bias units. I've been told by someone I trust in these matters that the optical-bias helped a great deal with maintaining the bias and even more with overall reliability.