@STEVIER

That won‘t be an official supported setup and there would be a delay between video and audio of at least 75ms. But if that is ok for you, on the technical side it just would be possible. 
But you would have to get an analogue output signal from tv like via headphone jack or via a hdmi arc to analogue converter. 
Also audio of an AppleTV device via Airplay would work with a pair of Eras. That way there won’t be the delay issue. 

You might want to see if your TV has bluetooth output, that way you can connect that way instead of through a wired connection.  I use this method for my bedroom TV, and it works fine with a delay that isn’t really noticable.  I would not recommend this for any ‘serious’ TV watching though.

However, you said this is for your garden bar?  outdoors?  If that’s the case, you might want consider using a pair of Move 2s as the are designed to be used outdoors, although you should still bring them inside when not in use.  Or you could setup outdoor speakers with a Sonos amp, which is designed to connect directly to a TV.

Thanks to you both for the Help….

@melvimbe the bar is a 4x5.5m solid build space...so a permanent fixture...although thats a great solution for outside living...(but in Scotland its about 10% of the year...lol)…

Ive yet to purchase the TV...so I may upgrade to OLED and swap over the main TV in our living room...or just buy another smaller as thats a 75” and may be too big… Ill defo check out the Bluetooth out on the living room one tonight as well...

@Schlumpf I’m gonna check out the livingroom tv that I may swap over as option...to see what can be done…

Overall Im still liking the idea of twin Era30’s though as the simplicity and sound should be great…

Thanks again @melvimbe & @Schlumpf …

STEVIER

@melvimbe & @Schlumpf ...on a slightly different note...would a single sounder above the wall mounted tv be easier...Ive just noticed that the larger Arc also can be used to just play music without the tv being on...but in reality...would it be powerful enough / a good fir instead of the Era 300’s to just have the single item installed that would do both jobs…?

As I dont have an Arc...I wound if anyone else uses in this manner…

STEVIER

@STEVIER 

For music outdoor use I really wont recommend a Sonos Arc because imo it hasn’t got enough power and not a wide stage. 
I would choose a pair of Five or even better a Sonos Amp with some powerfull outdoor speakers. 
The Amp btw would also offer a digital input. 
As a level below solution a pair of Move 2 or Era300 probably would do the job also, but with less punch. 
just my 2 cents…