The Sonos HT speakers, like most speakers, tend to just play the audio sent to them at the volume set for the device - different types of audio codec for TV, including PCM stereo, Multichannel PCM, Dolby Digital 2.0 or 5.1 and DTS etc. may output at different volume levels and this may also be down to the sound recording and production by the engineers too. So things can and do vary. In some cases the sending/receiving devices may use some volume-level normalisation, but Sonos (and I presume Sky too) do not interfere with the audio and simply play it back as intended by the Engineer. 

I understand that Sonos try to leave things as original as possible and not unnecessarily interfere with the audio received, but perhaps check with Sky to see if their sending devices maybe able to level out the volume in their audio-out settings - If not, then I’m afraid you may have to use the ‘TV remote’ volume control, or I guess you could get your TV to transcode all audio en-route and just output everything in PCM stereo, as that may perhaps brings things a little closer, but you will likely still encounter some differences in the way things were originally recorded/engineered etc.

Thank you for the detailed reply, would having the volume limit on Sonos at a lower level help also, sorry bit of a novice on this 

thank you 

There is a volume-limiter in the App, but it will simply adjust all audio output - maybe try the Sonos Night Sound/Speech Enhancement features instead - see these two links:

• https://support.sonos.com/en-us/article/reduce-loud-tv-audio-with-night-sound
• https://support.sonos.com/en-us/article/make-dialogue-easier-to-hear-with-speech-enhancement