Tapping to either side of the slider button will increment or decrement one click. 

Thank you ​@jgatie , that is helpful. Did not know that.

However , want to highlight that , when one is operating the phone in one hand tapping on the right to increase the vol is fine however reducing is difficult as the tap can hit the tiny speaker icon and it goes on mute. It is a pain and not a great experience. The UX can be much better and I hope the engineers at Sonos reading it. 

Some stuff gets back to the engineers from the forums but if you want to insure your suggestions do, it is best to call Sonos and discuss with the support folks.

​@Vatsa 

I agree tapping left at low volumes doesn’t work well because of the lack of line space that end.

What I find helps at lower volumes is to touch the circle, then drag your finger downwards so that you can see the circle - then slowly move your finger left or right. It’s far easier to adjust for small, lower increments than when your finger is covering up the circle.

I do similarly but with a kind of roll of the finger. Agree though: big + and - buttons would be much better. 

I move the slider all the way left and tap right in that case. 

​@Rhonny  - thank you that works better. I am learning so much now even though i have been using the app and systems for more than 3 years . Thank you

​@nik9669a  - thanks for sharing the sentiment.