WMP good but for the addons we have to pay,,.
other than that try Jetaudio free ,, its really fantastic has lot options ...i'm using retail version which has more features like audi & video conversion
try SRS Audio box equalizer, i WMP they had had an option for using if you installed & its listed under View->enhancements->SRS WOW effects
i mostly use jet audio for both audio & video, bcz for its sound effects,, i also have vlc , media-player classic with klite codec pack & WMP11.. but none matched audio quality with jetaudio for me..
just try basic free version first, if you satisfied you can get full version & it wort pay the money you paid..