The Era 300 is not designed to be your primary TV speaker, but you could connect your TV to the Era 300 via Bluetooth if your TV supports it. 

Thankyou for your reply. I was hoping to hardwire it. Ill just look at the arc or some type of connection with the bridge.

Cheers 

You could Connect ERA 300 to a stereo analog audio TV output using the ERA USB adapter.

I have an LG C9 TV and the Virgin Media V6 TiVo - the TV supports a Bluetooth audio-out connection, so it’s possible to pair the TV and Era-300 together and then play any TV audio to the speaker, including the V6 TiVo linked to the TV over HDMI.

I will add I don’t recommend the above, as my Sonos soundbar works far superior, but just to say it can be linked

My son has done a similar thing with his Amazon Fire-Stick and linked that to an Era-300 stereo pair, using Bluetooth.

When away ‘glamping’ in the camper-van I have linked a Fire-Stick to a Sonos Roam and that wasn’t too bad and sounded much (much) better than the 12v TV’s own internal speakers.

Thankyou for your detailed response. 

Looks like the it's the sound bar for my set up then.

I also use my Era 300 as a stereo pair linked with bluetooth on my Phillips ambilight tv.it works great and if i look at my tv settings my tv sees my sonos speakers as ‘audio out’ 

i only have one problem: my audio sound is changing after a while into a hollow sound…sound from far away like a metal sound.

If i change my hdmi output channel on my tv and change and come back you get a message ‘a/v optimization successful ‘ and then the sound is normal again.

how is it possible? 

Might it be a TV issue? Have you tried any other Bluetooth speakers, just to see if a similar thing happens with those? If ‘Yes’ but the issue still appears to be Era-related then, whilst the speakers are in range of the WiFi network, after reproducing the issue, it maybe best to submit a Sonos system diagnostic report from within the Sonos App, note it’s reference and then contact/chat with Sonos Support Staff via this LINK and see what the Staff can perhaps suggest to resolve the matter.

FWIW …a friend of mine has a similar setup and they are using BT linked Era 300’s to a TV (not a popular TV brand, but I’m not sure of its make/model) and he is not hearing a similar issue, although occasionally he groups the speakers with a Sonos Five and either one or two Play:1’s and very occasionally has a minor lip-sync issue with the video on screen, but he’s not noticed, or mentioned. having a metallic sound

I saw on google and someone says it is a audio delay problem from the Era 300.This hollow sound is because there is a audio delay from 75ms

Its fun to experiment with these era 300 but its not made for stereo pair for tv sound.It works but not 100%.

i will buy a gen2 soundbar soon and put the Era 300 on the background.

All Sonos analog line ins have a 75ms delay, it’s built in to the software, so that Sonos can play the content across multiple speakers in multiple rooms without interruptions.