Funkifized

I love my minidisc recorder, sound is good, recording with mic on my band gigs. However, recording to the a digital file that I can edit and email is a problem. I've got the MZ-R700 that I'm trying to record to my Toshiba Satellite C675. The only input jack into the PC is the microphone jack. Using AVS Audio Editor software as well as trying Audacity, the sound becomes inconsistently muffled. I'm using a stereo mini-jack to stereo mini-jack cable to do this. The sound on the minidisc is awesome; the Audacity file is quite muffled. What to do?