“DVD-Audio” is a specific high-res format. There is software around for making them, but 1st you’d want to clarify exactly what this player is playing. Do you have a disc you can post the contents of?
From what I can see these are proprietary machines playing proprietary audio files that are encrypted. Its a dead format to be sure, and the players sell for about $30 on eBay. The disc drive in the player probably has more value than the Musak hardware.
Virtually any portable audio player can accomplish the same things, if not more. Even your phone can.