hi, i'm new here and i'm having problems recording. I bought a uni-directional dynamic microphone IMP.600 off of ebay for 13 bucks and i'm using a 60 foot extension for it. I'm using the port beside the headphone port to plug it in but I can't get anything to come through. I used it on another computer without the extension and it worked but very very quietly. Does the fact that the inbuilt mic still picks up sound mean that it is the connection? I've read a little about preamps and that stuff. I want the highest quality sound I can get pretty cheaply. I think I made a mistake getting a dynamic mic. I'm using garage band on an new iMac. any help?