Up for auction on Ebay is this Clearsound kit. Originally sold for $300, this is an inexpensive Sony CD player, a backpack, and a Clearsound amplifier. Clearsound is touted by Scientology as a method of tape restoration to increase the clarity of tapes of L. Ron Hubbard from the 1950s and 60s. It was used to record the sound for the 1990 Tom Cruise film Days of Thunder.
In this case it’s a small amplifier that plugs into the CD player, and has a headphone jack, intended for listening to lectures by L. Ron Hubbard that use Clearsound technology.