I use Logic Express 7. I bought a MOTU UltraLite, which comes with Audio Desk recording software (a scaled down version of Digital Performer). I was curious and thinking of giving Audio Desk a try. Specifically, there is a plug-in called Preamp-1 which the manual says "... simulates both subtle tube pre-amp warmth and drastic distortion effects." If you have tried this software or plug-in I am interested in your comments.