Adding wireless speakers


We recently bought a vintage Grundig Rossini 2 stereo and I am interested in adding accessory wireless speakers to hear the records outside without running new wires. 
I presume I’ll need some sort of Bluetooth transmitter to attach to the existing speaker wires. 
that’s what my logic tells me. 
Any help would be greatly appreciated.   

drewvb01

You might get more response if you post this under 'Speakers' or 'Misc Audio' or something else other than 'Analog'. 

I think this is impractical.  This console is ancient (more than 50 years old) and I cannot find any information on-line about any external connections.  

Here's a thread about a slightly newer model and it makes me even more pessimistic about interfacing with your model. Grundig

If you have decent WiFi, consider an independent, wireless streaming speaker for outside music.