I recently purchased a new Onkyo receiver, Sonos speakers and amp.  The installation and configuration was fairly simple and straight forward.  I am very happy with them and everything is working together, but I have not been able to able to overcome the volume limiting.   I have Polk audio speakers and anyone that has had Polk audio speakers knows you need a good amp,  they are very power hungry and will not even operate until you have raised the volume to a higher level. 

I have volume limit on sonos turned off and I have set my Onkyo amp to start at the volume that will start to power the speakers.   When I play music from the sonos app to my onkyo / polk audio the volume slide starts are near ½ to ¾ volume on the slide bar.  Leaving only about ¼ of the bar remaining to raise the volume.   When I move it to the max volume on the sonos app it is really only about ½ volume limit on the amp.  I can still adjust with amp controls.   In addition the sensitivity of the volume control with the sonos amp is too sensitive,  a slight adjustment with the sonos slide bar will take you from not hearing anything to very loud with very little adjustment

How do I adjust the volume limiting so I can use the full functionality in my amp?