I have a SiS 7018 sound card which is pretty basic, it came built into the computer years ago. Well anyway, for years it was doing an OK job but quite recently I've been getting really tinny sounds not just on PC speakers but on good quality headphones too. Everything sounds distorted and tinny, like laptop speakers. I'm not sure if the sound card has just broken, or if somebody has tampered with settings on this computer and I need to rectify something.