You will need a RCA to 1/8″ headphone jack cable and a MP3 encoder with the option of recording from your line-in. I use Musicmatch. There are some expensive alternatives if you are fancy. This will still get the job done though.

Attach the output of your stereo amplifier to the back of the PC.

In MusicMatch, select the desired bitrate for the MP3s. 128 Kbps will work. If you want to make it a little higher quality – try 160bps or 192bps. It’ll take up a little more room, but hard drives are cheap.

Set the recorder source to Line In. To set your recording level, play the cassette or record and open up your computer’s Recording Control. (You’ll find that under Control Panel > Sounds and Audio Devices). Drag your mouse up or down on the slider to adjust the recording volume. You’ll have to listen back to the recording to check out the volume before you’re satisfied that it’s not too quiet or overmodulated.