Recently I upgraded my amplification by adding an Audio Research Ref 3 preamp along with a full Monty refresh of my McCormack DNA 1 (now Ultra Platinum). I have discovered that really good tube preamps work well with Thiel (prior was Audio Research LS 9). The McCormack DNA 1 with the Plitron transformer- wait for it- can "transform" Thiels. The amp can dump current far beyond what is necessary to control the 3.6es. Steve McCormack should be recognized along with Pass, Bascom King and Dan D'Agostino et al. as a Hall of Fame amp designer.
Finally, cables matter more than I thought. Power cords are Shunyata Alpha HC (C-19 on ARC Ref 3) and ICs are Audioquest Columbia balanced XLR on all ins and outs.
The Thiels dutifully reported every change I made. The system is warm, musical, revealing but absolutely none fatiguing. It provides a large and detailed sound-stage and a "coherent" presentation of the source material. Yup, poor recording are not sugar-coated, but the good stuff is really, really good. I think that there are now "better" loudspeaker systems with more modern technology available, but make no mistake: Jim Thiel made a major contribution to the art and science of speaker design that has stood the test of time. His speaker designs are relevant, correct in concept and execution and timeless. Thanks Mr. Thiel.