I agree with your assesment Drjay. Im using my NAD M51 DAC as preamp straight to my Parasound Halo A21 right now. The sound is not bright at all on good recordings and is VERY open and clear. I have downloaded several albums from HDtracks.com and have found them simply amazing on my system. I have a CJ MF2100 but it simply doesn't have the guts to push the Thiels. I also tried a Vincet amp and it just didn't have the low end grunt that was needed. Im pretty happy with the Parasound so far considering its price point. The trick with the Thiels as Im coming to understand, and that most people have already said on Audiogon, is that you need lots of clean power. If the amp cant deal with the bass then the highs sound clean but the bass cant starvs giving the impression of a bright speaker. However, if you feed it gobs of clean power and allow the bass to have its day, then the speaker balances out nicely. Not to say the the Thiel has gobs of bass, it doesnt, just accurate for whatever bass is there. However, they are a VERY revealing speaker so a bad recording can hurt your ears.
I was considering a Balanced preamp, but Im not sure I like the idea of another potential distortion between the sorce and the amp. I like the idea of less is more. But Im open to comments/ and or correction on this.