Cassette tape players use a read head where the magnetic field from the tape is directed through an induction coil. The induced current in the coil is then amplified and sent to the speakers. Now I'm wondering if magnetic tape technology could also work with a permanent magnet that vibrates from the changes in magnetic field in the tape (for playback) or that is made to vibrate externally to create a changing magnetic field on the tape (for recording).
Obviously this is just a theoretical question as I'm not going to use a permanent magnet tape player for anything. I am just wondering if this would be possible with any level of sound quality.