It’s not TV HT surround sound, it’s just a stereo TV audio source. However the answer (to some degree) is ‘yes’ you can add a Symfonisk bookshelf speaker to your Sonos system and ‘group’ that speaker with the Play:5 to play the same audio on both speakers.

I’m a little surprised that you are not seeing some small delay/lip-sync audio issues with the TV video on screen, even with just the Play:5, as there is often a small delay with such line-input (usually around 75ms), but if you’re happy with that, then I guess it matters not.

hello

I get round that by going into the audio settings of the TV and adding 80 ms of delay so the audio is in sync.

Yes I agree I think the whole “ more delay means better audio “ BS that Sonos spouts is rubbish but there are ways round it.

Grouping a speaker is not the same as surrounds bonded to an actual Sonos Home Theater device.  In your scenario, the Ikea speaker will be playing the exact same 2 channel stereo signal as the Play:5.  

I know I never said I am grouping it

please see the post title.

Forget about the grouping comment.  There is no way to connect an IKEA bookshelf (or any other Sonos device) to a Play:5 for use as a surround speaker. 

Are you adding more audio delay than the line-in already creates, or does your tv allow video delay and that’s the adjustment you’re making? 

Just to reiterate, the output of any TV’s headphone jack is only ever going to be stereo, and won’t carry any separate surround information. And of course, the Sonos Five/PLAY:5s do not have the capability to interpret a 5.1 signal to separate out a surround signal on their own, even if such could be carried to their line in, which is also only a stereo input. 

Secondarily to that, any line in on the Sonos is subject to that minimum delay of 75ms.

If you’re feeding a line in on a Sonos device, you’re feeding it at best a stereo (front only) signal, and not a surround signal.