I wanted to do this once and the quickest way I found was to Batch Process the mp3s with SoundForge (get a free trial)

http://www.sonycreativesoftware.com/bat ... nd_forge_9

yep i'll back up nohitter151 on that. just start mm up and get the playlist ready, then start audacity and record the songs in it then save them as mp3 or ogg or wav.
if you like the eq settings you have in mm.

but if you want you can just open the song files with audacity and use it's equalizer under it's effects menu. and adjust the song's with it, there are more freq sliders on it's settings then mm has. you would then save the song as a different file name and then move that file to the usb drive or if the song is sounding better then it did before in mm, just replace the one you started with.

roving cowboy / keith hall / monkey hi fi

You'd have to re-record the tracks with a program like Audacity.

I want to output mp3s to a USB key for the car which have been equalized or processed with DFX. I know you could do it with Winamp, but I want to process a playlist for example just for playing in the car. ANy ideas how to do this?

Jeff