degrading quality when converting cassettes to mp3 with audacity
I have encountered a problem with converting my cassettes to mp3 using Audacity.
I have converted 11 cassettes (around 90 minutes per cassette) into mp3, which has all worked fine. However, i've now went back to do some more and the quality that Audacity is playing when recording is totally unlistenable. The cable is the same, I just bought it three or four weeks ago - it's just a male-male audio cable. It's quite short, but I have the stereo next to my laptop just now for this purpose.
The cassettes I am using now are actually of better quality than the custom cassettes I was using in the first 11. I know they play and work fine as the stereo plays them in great quality.
Does anyone know what I could try to resolve this problem? Any help would be much appreciated.