Hi. The short answer is no. That cable is not usable in your situation. 

If this digital out is not optical I can only assume it is digital coaxial? Is that the case? If so then all you need is a digital coaxial to optical converter. 

Hello John 

Thanks for taking time to reply.Yes it is coaxial output but I don't want to use this, however I am thinking of getting a HDMI audio extractor which I can connect one end of it to HDMI arc on my tv and another end to the optical output of playbase using the supplied optical cable. Will this work? Something like what is shown in the picture below 

Front 

Back 

Hi.  I cannot tell from the images, but it would need to convert HDMI-ARC to optical, which is not the same as HDMI to optical.

I can’t imagine why you wouldn’t go for the simple and cheap option of coaxial to optical.

If all your viewing is from external sources such as a cable box, you could potentially run the audio from there to the Playbase, using a switch if necessary.

Thanks again. I had a chat with the seller he says hopefully it works from the HDMI arc to optical. Not sure yet but thinking of  giving it a try.

About the coaxial cable will it support dolby digital 5.1? 

My viewing is from different sources, xbox, apple tv, cable box and chromecast so I thought I can adopt this method of connecting all the sources to tv and then use HDMI arc to return the audio to the playbase using the mentioned audio extractor. 

Coaxial to digital is certainly capable of passing through DD5.1, although you should check the specs if you consider getting one.

I was thinking of something like this (random selection, specs not checked!)

https://www.amazon.co.uk/Cable-Mountain-Digital-Coaxial-Converter/dp/B001U7GW68

The approach of feeding all the inputs to the TV and then a single out to Playbase is the recommended Sonos approach and I am not suggesting otherwise.  Linking direct from sources to Playbase, bypassing the TV for audio, is just another option.  There can be advantages to that. - some TVs won’t pass DD5.1 from external sources and some introduce audio lags.

Personally i would order a coaxial - optical converter online, give it a try, and return it if it is unsuitable and consider other options.

Alright noted I will check if that sort of coaxial convertor is available on my amazon store here in Singapore. I remember trying this for my old cheap soundbar 2 years ago couldn't find one before. Let me try again. 

Thanks again. Cheers