hello please help.
this will be a sim pe answer for sombody.
i record music from a set of decks and mixer line out red/ white phono leads into mic in on my pc.
the sound quality is terrible. but if i play a pre recorded mp3 through audacity its crystal clear. im recording to loud. as i look at the record in bars bouncing up and down where abouts should they be???
also when i look at the main wave forms how should they look???
cheers mike 
The problem is right there - the outputy from your mixer is at line level whereas microphone inputs are designed for microphones which have a signal strength around 1000x smaller than line level - the result > The signal from your mixer is overloading the microphone input of your computer. You may be able to get round the problem by turning the volume way way down on the mixer, but this is not recommended and you may easily blow up the microphone input of your sound card. Much better solution is to get a sound card that has a “line level” input.