Thiel used Krell amps in the design of their speakers (especially the 3.6s ) which are an older design. They are starting to branch out to other amps now that Krell is in the speaker business. I bought a pair of 3.6s last summer and realized that I needed a much bigger amp to drive them. I bought a used Krell KSA 100 MKII it only has single ended inputs but it was built when they were truly class A amps full output. It puts out so much heat they used fans to cool it as opposed to just large heat sinks. Anyway, I also picked up a Krell KSP 7b which was in mint condition and sounds very good. But recently I found a web site by Arthur Salvatore who had a list of reccomended components among which was a list of preamps to try. On his recommendation I purchased an Audio Research SP 8 and I have to say they are a great match. The sound is warm yet very detailed. Vinyl is fantastic. I recently heard a AR ref 2 with a Krell FPB 200 and I think my vintage combo blows it away. According to Salvatore some of the old arc gear was the best to own. The arc Krell combo blew away the Krell Krell combo. However, I caution that newer Arc stuff does not sound anywhere near as good. In terms of the amp though I would definitely stick with the Krell. However, a great preamp will give you the subtle inner detail for days and days and days and not just the macro dynamics. The sound should sound good and detailed and low as well as high volumes.
