I hope the CD player is connected to the cloud so he can get important security updates for his CDs. Then there might be a way to add some personalized product recommendations between tracks...
Ads between the tracks, maybe a special format and an agreement with the CD player manufacturers that these can't be skipped or turned down.
followed by an agreement with the headphones manufacturers that the device be ratchet strapped around your head, with DRM on the headphone jack to enforce this