Equalization/NR before burning?, Reducing treble/boosting bass before burning. Options

I'm happy both with the ability of iTunes to burn CDs and with the ease of transferring even cassette tape files to the iTunes' library. But in the case of the tapes I'd like to be able to reduce the noise in the treble (not just tape hiss, either) as well as boost bass frequencies.

1. What's a program that allows some equalization and in real-time (so you don't have to keep playing it to see if it worked)?

2. Is the equalization best applied before, during, or after the music has been recorded and saved to hard disk as an AIFF file?

Thanks in advance for any ideas.

Sam

Thanks much for the help.  I've been recording with Coaster, which strikes me as every bit as effective as Sound Studio, but neither affords much noise reduction or equalization as far as I can tell.  Saw some negative reviews about Ray Gun, and I don't think it has real time preview.  Spin Doctor is probably worth a try.  I had trouble making Toast work with iTunes, but I see that you can now download Titanium upgrade (from Roxio.com) 5.0.1, which apparently takes care of the problem.

Mac users, incidentally, often seem less appreciative that the competition.  A Time Magazine editor wrote a whole page article last month lamenting that PC users could not burn CD's effectively because they lacked a program like iTunes.