The Play:5 is not really meant for this type of configuration.  There is always going to be a 70 ms delay on the analog Line-In.  Only the Playbar, Playbase, Beam, and Amp are designed to play in sync with video.

Thanks so much for the quick reply. SOO is there any easy way or small add on I can buy to make it work? I have seen on here people talk that it is sync’d, so it seems to work for some people. Anyway, appreciate you help 

Have you updated your controller and system to latest firmware?  If so, when you go into the line-in settings you will see an Audio Delay setting.  You can at least ensure the delay is set to the minimum.  But as @jgatie says, you cannot get rid of if completely.

The delay is deliberate to create the buffer for multiroom audio.  That is what the P:5 is designed for. But at the minimum it may not be a problem for a boxing match.

Incidentally, the headphone jack is not a great option for the audio from the TV.  If you decide to persist with the P:5 as a TV speaker, you should consider using the digital optical out if your TV has one, with a digital to analog converter.

Just wanted to thank you all so much, what an amazing community. It worked a treat, tiny lag. One more questions, can I plug an old amp connected to a vintage record player into the back of a play5 as well? You guys are awesome. 

If the amp has a pre-amp in it, yes. The Turntable uses a ‘phono level’ output, which is why most amplifiers have a specially labeled ‘phono’ input. Sonos expects a ‘line level’ input to work, which is what you get out of a pre-amp, or the tape out on many receivers. 

Thanks Bruce, how would I know what a pre amp looks like? 

It would be a small device, probably near the size of a pack of cigarettes, with a power cord, and RCA jacks in from the turntable on one side , and out to any device on the other. 
 

Wwhat is your turntable plugged in to currently?