I am looking for some sort of adapter that can take audio from an AUX plug and transmit it over bluetooth to a speaker or headphones. For now i've only been able to find the inverse, streaming audio over bluetooth to a speaker that doesn't have bluetooth capabilities on it's own.

I'd realy like to connect my bluetooth headphones to my old vinylplayer.

Does someone know if something like that exists?

Is this a feasible way to add Bluetooth capability to non-bluetooth speakers? I'm looking to buy a pair of basic computer speakers (or possibly powered monitor/bookshelf types), many of which have only wired inputs, but I'd like to be able to use them over BT from devices other than my desktop that they will stay connected to.

I am thinking I could connect a Bluetooth receiver dongle (like the ones pictures) to the speakers' input jack, but would it sound terrible? I'm sure it depends on a lot factors and there's a good reason that some BT adapters are $10 and others are $200.

Anyway, let's say I want to add BT to my Bose Companion 2 Series iii, which have only a standard 3.5mm input jack, how much sound quality will be lost if I use a cheap vs. expensive BT adapter? What about adding BT to a higher end speaker via optical input?