looking for advice from anyone who use a laptop in a live setting

[Oldrottenhead]

hi looking for help for a friend of mine, he got a new laptop to use to playback his backing tracks when gigging, the soundcard has only line in and headphone out sockets. when he uses headphones it sounds great but as soon as he runs it into his pa/desk/amps (not sure of his set up), he gets an annoying buzzing sound. he checked leads they are ok. not sure what soundcard he has but it is a standard dell laptop. would it be worthwile replacing the soundcard, with a better one, ie one with a line out, or is there some other possible solutions.

[Oldrottenhead]

got it sorted need a ground loop isolator