As both Russ and Ron have emphasized, line-out on the MD would be far preferable to headphone-out. But if your MD doesn't have the line-out, you can do it with headphone-out, being sure to set your line-in volume on the soundcard to a level that eliminates distortion. This won't give as clean a sound as if you had a line-out jack, but it can be acceptable if you're careful with the sound levels.