I agree with most of the points above. I have found on an absolute basis the preamp has a larger effect on the overall sound of a system than an amp (this is obviously a generalization).
That said, Mapman's right in that if your amp won't drive your speakers properly the rest really doesn't matter. And since most Thiel speakers are demanding and quite picky when it comes to amps it's probably particularly important in your case to get the amp right first, then find a preamp that synergizes well with your sound preferences and the amp itself. I'd follow that strategy and let the costs fall where they may.
Best of luck.
That said, Mapman's right in that if your amp won't drive your speakers properly the rest really doesn't matter. And since most Thiel speakers are demanding and quite picky when it comes to amps it's probably particularly important in your case to get the amp right first, then find a preamp that synergizes well with your sound preferences and the amp itself. I'd follow that strategy and let the costs fall where they may.
Best of luck.