Used Krell FPB’s often times recapped, can be regularly found at near bargain prices. IMHO, great sounding amps that are truly up to the task of powering many of the Thiel’s.
https://www.hifishark.com/search?q=krell+fpb
I worry that we sometimes over generalize amps/speakers compatibility.
Thiel CS 2’s:
https://www.stereophile.com/content/thiel-cs2-loudspeaker-measurements
quite a bit different than Thiel CS 5’s:
https://www.stereophile.com/content/thiel-cs5-loudspeaker-measurements-0
Krell FPB 600:
https://www.stereophile.com/content/krell-full-power-balanced-600-power-amplifier-measurements
quite a bit different than
Krell KAV 300i:
https://www.stereophile.com/content/krell-kav-300i-integrated-amplifier-measurements
Don’t get caught up in the hype of the gurus. Check the specs, and better yet check the independent measurements. Doing this will save a lot of wasted time and money, making one’s short list much more manageable. Then sonic preferences will be the final arbitrar. Power amps capable of driving many Thiel’s are often big and heavy. Shipping and set up can get expensive and inconvenient.
True doubling down is really just theoretical. In actuality amps that tout this typically understate the power into higher impedances. In effect there is a window of operation into various loads that will determine appropriate application. Still with that said, I suspect that an amp with less high impedance power that can come closer to doubling down and down again (if necessary for the application) might have some advantages over a high powered amp that still outputs the comparable power into lower impedances, After all the extra power into higher impedances might be wasted. Of course as long as the amp is up to the job, the sonic qualities that are unmeasurable might sway one differently.
Another concern I have is when some say that Jim might have recommended a particular brand of amp at a time when the Thiel products had different amplification requirements than later models. What was recommended then was for then. What came later might get very different recommendations.
I strongly believe that the best course of action is to lean on the side of caution. Check the impedance of a particular Theil model and then double that down to the round impedance divisible for that particular speaker model (e.g. 2.4 Ohms to 2 Ohms) then multiply the minimum recommended power for that particular Thiel model down to that impedance (e.g. 100-400 Watts to 400-1200 Watts). This will be especially true with tube amplification. Of course different rooms and volume expectations will vary power requirements. Personally I think the old audiophile rule of thumb to double the minimum recommended power, though not hard and fast, has proven to be well time tested. As has been pointed out being stable into short term peaks is not really good enough for many Thiel models.
