Did you set your system up for rock, jazz or classical from the get go?
I am setup to play anything from movies to Telarc classical recordings, from AC/DC to Duke Elington, from Black eyed Peas to Sara K. It is a myth that you need different systems for different genres... aim for accuracy & neutrality rather than a warm or harsh system and you will be ok. On a good system, if it sounds bad then it is a problem of the recording quality (which can be bad in all genres and is only consistently bad in modern pop music that is made "hot" or loud for CD's = try google on "CD Loudness Wars" and you may discover why vinyl is still popular with people old enough to remember how good pop/rock used to sound)
The old bell curve rule applies here....if your system is setup right then the maximum of recordings will sound good (center of the bell). Any system set up for a particular target type of sound will be entirely limited to sounding good on a smaller portion of recordings (somehwere in the tail of the bell).