I love my SST stuff, but I agree with others here; try a different preamp. I would also recommend that you try some Analysis Plus interconnect and Oval 9 speaker cables. They are a fuller-sounding but very (subjectively) quiet cable combo with powerful bass and smooth highs.
Lets see, Classe cd players are a bit on the cool or edgy side...coupled with a preamp that is on the light side, and adding in the Thiels which are also known to be a bit "bright". Ouch. It does sound like negative synergy here. I don't know what Accustic Zen sounds like so....I would say that your amp is not your problem. Also, you might want to consider a tubed cd-player. In fact, they might be the first place to try.
Lets see, Classe cd players are a bit on the cool or edgy side...coupled with a preamp that is on the light side, and adding in the Thiels which are also known to be a bit "bright". Ouch. It does sound like negative synergy here. I don't know what Accustic Zen sounds like so....I would say that your amp is not your problem. Also, you might want to consider a tubed cd-player. In fact, they might be the first place to try.