Here's a little device that might be suitable. The good news is that it will only cost you a total of £5.61 to find out:
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It plugs into the headphone socket on your Technics Tuner/amp.
It should transmit the audio wirelessly 'up to 10 metres' to your soundbar (which has a built-in bluetooth receiver).
It comes with an instruction manual. You will see from the picture that there's a silver plug-to-plug adaptor fitted to it. I would remove that and use the plug-to-plug lead that they supply (to avoid physical damage to the Technics' socket).
It's got a built-in rechargeable battery, said to be good for 8-10 hours after a 3 hour charge.
Good luck. If you decide to go for it, tell us how you get on.
P.S. You might have to experiment with the volume on the Technics to avoid distortion being sent to the soundbar.