Late last year I purchased a BBE Sonic Maximizer, for both recording music and enhancing music I listen to from my PC into my stereo. While I haven’t recorded all that much music lately, the difference with the Maximizer on or off is astounding.
The bass is boosted without becoming boomy, the stereo separation is dramatically enhanced, and there is a treble and/or presence level EQ enhancement that really clears the sound of music.
It sounds particularly amazing with techno and electronica. My device version is the 882i.