Best amp for Thiel 3.6 speakers?

I've had great success with the older Krell line / the KSA and MDA series. The least powerful is the KSA-150 and the most powerful & mighty MDA-500 mono blocks. I have all 3 of these rotating in my system which was built around the CS-3.6's...Try a KSA-150 (plenty of power/150-300-600-1200 @ 1 ohm) first with MIT MH-750 cables. Both used would run about $2k to $2.5k and you can purchase a second KSA-150 at a later date and have them converted over to the admirable MDA-300 mono blocks if more power is needed, ie. large room or Stupid Approved listening levels. Thiel even used the MDA series during the design back in the early 90's.

I beleive the Thiel recommends using CLasse with their speakers. I've never heard it but thiel reccommends it and everyone who tries it loves it. I hope this helps.

Using ML 333 with mine. It sounds a bit laid back, I think this is due to the ML amp. Otherwise, very detailed, good soundstage, and well-controled bass. Very revealing of any weakness of front end equipment and bad recordings. I am running a pair of Transparent Ultras speaker cable. The rest of the system consists of ARC LS 2B MkII pre + PH3 SE for phono; ML #37 (transport) + Genesis Digital Lens + SFD2 MkII (D/A) for digital; Michell Orbe SE + SME V + Benz M2 (woodbody) for analog. MIT balanced interconnects, Illuminati digital cables, Eletra Glide powercords + PS P300. I am using NOS tubes and different cones/vibation devices to fine tune the sound. I've also had my Pass Aleph Os running the 3.6s for a little while. Not enough power, but great with small ensembles at low volume. It's in my bedroom powering my second system now.

Pass Lab x-150 or 250

Classe amps sound wonderful with Thiels, as a matter of fact I had the pleasure of meeting Jim Thiel about 10 months ago and he too loves Classe gear with Thiel speakers. Thiels tend to blow tweeters easily, so watch out with the volumn and size of the amp. Consider a Classe CA201 or CA 301 amp.