When I had the Thiel 2.2s, I had hooked them up to a Forte 6 (the 200wpc version of the 4A), Krell KST-100, and Pass Aleph Os. The Aleph Os (60 watt class A) had the best midrange, and overall warmth that made them a great combo. I've since upgraded to the 3.6, but still kept the Aleph Os. It's not powerful enough for the 3.6, so I have relegated it to powering a pair of Unity Signature 1s in my second system. This great amp is designed by Nelson Pass and put Pass Lab on the map of high-end. You should be able to find it for under $1500 these days.
FrankC