Welcome to the Bose Community!
I'd be happy to assist you with your question today. Can you please confirm the Make/Model of your television so I can determine what options are available?
Jeff G - Community Support
It looks like your TV has a Composite (red/white/yellow) input on it. I would recommend using a stereo 3.5mm mini-jack to stereo RCA cable to connect the echo to the red/white composite inputs on your TV. If you set your TV input to Composite, you will be able to hear the Echo Dot through the SoundTouch 300.
I have created a diagram to show how everything should be routed. I hope this helps.
Let me know if you need any further support.
Thank you for the help. The only issue with that setup is that if I speak to Alexa I can't here the response unless I change the input on the tv. Not optimal. Again thanks