Best pre amp for Mcintosh 501s

Help needed going to the next level. Using a Mcintosh MCD500 CD/DAC wired with Cardas Gold Ref ICs straight to the MC 501s. Ascendo M-S speakers w/ Kharma GR SP cables and a Wadia 171 w/ an Apple I-Touch as digital source, also connected with Kharma Enigma cable. On some tumes the highs seem a little harsh. I am also wanting to improve the pin point imaging and sound stage effect so the performers are in the room.
What gear will give me this, a good pre(5K-7K) better ICs or replace power cords or anything else? Thanks
The 501s are anything but harsh. When I owned them, I thought the C2300 preamp complimented them well. You can roll in tubes to fit your sonic preferences. I liked Psvanes in mine. A step higher would be the C500t, which should be available near your price range used.