Bit wish, there is nothing wrong with Audacity. Something is wrong in your signal chain. Make sure you're using a stereo cable into a stereo line input. You may have a mono cable, you may have a microphone input, either will cause problems. If you don't have a stereo line input on your computer, consider investing in a small audio interface, or one of those mixers with built in interfaces. Even a shitty behringer one would probably be an improvement.
And for the record, I work in Digital Performer or Audacity, depending on the complexity of the work.