OV9

Any recommendations? Ideally not battery powered - mains or USB preferred. And would optical or AUX connection make any difference?

Looking at this:
Amazon Link - Avantree

Quick Google suggests aptX is necessary? FWIW they'll be used with some AKG Y50BT's.

Been looking at something like this, to connect my CD player to, to use bluetooth headphones or speakers. Intrigued by this statement seeing as it has RCA input: 'Not compatible with ANY RCA output on back of AV Receiver / amplifier.'. Probably fine as my amp would stay in the loft and I'd connect using the RCA outputs or, iirc, optical out from the CD player, but still I'm not sure why this wouldn't be compatible.