Theil/Classe 6, and listener fatigue

I would "blame" Thiel-Rotel "combo"!

I owned Thiels for over ten years and found them to be amongst the least fatiguing speakers around. I believe this is a function of sheer accuracy. They are detailed and therefore some people who seldom listen to live music call them "bright". I suggest you try a different CD player first.

You may also want to try and change the angle of your speakers. If they are toed in, try moving them to aim more straight ahead.

Kadlec, You didn't mention any acoustic room treatments...if you have a lively room, you might want to treat the 4 upper corners, the side walls the center of the front wall, and the center of the back wall with some acoustic treatments. You can make these yourself from 2" foam and cover them with any cloth that works with your decor. Use hot glue and Velcro to stick them up. (Look at Michael Green Room Tunes for placement and sizes.) Then you can play with speaker cables and interconnects. I'm not fond of the B&K amps, they tend to be boring, 2-dimensional, and lifeless. I've heard the Theils MCS1's with Classe cd, amp and preamp and also thought they were a little too bright. But try the room treatments first, then the cables, and then you can start swapping amps or cd players.

I disagree with joe_coherant. I find the entire Theil line to very much on the fatiguing side. Way to edgy for my tastes in the highs. I would recommend going to a tube amp and/or preamp to tone down the sizzle of the solid state gear. Good luck, I can imagine what you are going through.