I've heard the BAT, the Aesthetix, the Blue Circle mentioned above, and I'll add another one - VTL 5.5. They are fine preamps. However, I've chosen to own the Audio Horizons TP 2.0, a balanced tube preamp. Audio Horizons has a home trial program. The fully loaded version (I own this one) costs less than $3.5K. I think it outperforms the other preamps mentioned above, but you can test that assertion in your own system.