Well, decompressing and recompressing your music will probably annoy you to no end if the compression while in car is a problem for your listening enjoyment.

Most CD's are normalized already anyhow. If you really want to nomalize your entire collection, your better off reripping to prevent quality issues.

Also, from my personal experience, the compressor is really nice. I have it set to only work in the car. I'm glad it's not done to CD's as this would distort things, but I do like having the easy option to do this while in an enviornment where it is useful. You should at least give it a try, as it's easy to install and remove from the empeg.