Had CS 3.6 for many years and of all the amps used the best match that I came up with were the Krell KSA and MDA series amps, A Krell KSA-250 was a staple for quite a long time with the Thiel CS 3.6
Detail and absolute control of the 3.6 was high on the list and the KSA-250 did not disappoint. They dipped down into the 2 ohm range but that never phased the older Krells. Even a KSA-150 works well if your room is not too large or you don't push to a ridiculous dB level. My old room was rather large so the KSA-250 and MDA-300's had more reserves for large dynamic swings.
Power output from the 150 and 250 was -
150 w > 8 ohm
300 w > 4 ohm
600 w > 2 ohm
250 w > 8 ohm
500 w > 4 ohm
1000 w > 2 ohm