That means the MP3 player, portable CD player or whatever you're using isn't writing to a physical medium. So how could it transmit its signal to the cassette deck's tape head?

My Bad.<P>You could get a Y-splitter and hook up your CD player in addition to your Mp3 player. Unless you can find some exceptional cable you might have to live with slightly degraded sound quality.

Well, while a lot of those same cars are still on the road, the Discman has now given way to the MP3 player. That's why ION Audio has released its Cassette Adapter Bluetooth.

With Cassette Adapter Bluetooth from ION, your car’s cassette player instantly becomes a wireless Bluetooth receiver. Just like that, you can stream music from any Bluetooth music player or phone.