All 3 preamps you've mentioned are excellent choices. I would also consider a Cary slp 90,94, or older 98 to fit your budget. The vintage mcintosh preamps were a little to soft and lacked resolution, the Cary gave my MC30's a little more bite and were a great mix. Was using Klipsh Forte and Heresy at the time and was able to do an A B comparison with the c20 and Cary slp90. Also had an MX110 at the time and the Cary won hands down for me.
