A little provenance here, however it looks like the seller rarely if ever sells audio equipment so where he/she came up with that price is beyond me seeing as they show a completed listed for a PAIR for less then the single being offered
There is no provenance, unless you include buying it from a surplus store. The rest of it is assumptions from a patchwork of maybes and someone I know told me that ... hearsay that doesn’t even make the connection.