Ineed some help with a simple math equation

Also important to understand how they eat power. Are they low impedance ? Difficult to drive due to high phase angle or low Z in the bass?

You may indeed need a very solid amp, but not necessarily need all those rated watts at 8 ohms.

Best,

E

As a Thiel 3.6 owner I wholeheartedly agree the more power the better (those speakers are excellent at high level transients, which is probably why they need power).

My suggestion: since the Thiels have an average impedance of less than three ohms from mid bass to 20khz, go with the amplifier that has the highest 4 ohm power rating at 1000 hz. (I assume those power specs are at 8 ohms).

bill10907 and gs5556

good to read that both of you guys enjoy Thiel speakers.
Please check out and join in the Thiel Owners Thread discussion
(under Speakers section). We all would enjoy reading about your Audio gear and musical journeys.

Happy Listening!

Your preamp will likely breath a little easier with the 400w/29dB gain amp if the amp's input impedance is equal on both amps. 

Almarg, Kijanki, eric_squires, gs5556, Jafant, bpoletti. Thanks for weighing in. I appreciate it, as I have a decent technical mind, but with sound and waves I'd say I'm out to lunch. Plus, I think the math just got harder. Here is some more info. The 400 and 500 is at 4 ohms. One is a classe amp CA-2200 (400 with 100K input impedance). The other amp is Pass Labs X250.5 (500 with 20K input impedance). My room is 20 x 24 and carpeted. I have the room set up with speakers at 5ft from the back wall and about 5ft from each side wall. The room has three windows, each covered with a matchstick blind as a difuser. Each side window is also protected by a 2x3 absorber hanging from the ceiling to block first reflection waves.
The pre is an ARC Ref 3. After the system and my ears are warmed up, I can take the "loudness" to 75%, after that, I think the sound starts to.... say, break apart a bit. So with the Pass, I'm hoping for 1. a slightly better amp and 2. just a little push in the "snap" (e.g., drumstick on drum skin), such as what you get with live music, at home when your stereo is loud enough, but without the distortion you get with live music (usually venue dependent).