Rega p3 and Yamaha AS1100


New rega p3 and Yamaha AS100.  Playing moderate volume between 8 to 10 o'clock runs great good quality sound. As soon I set to 11 o'clock volume on my amp, speaker start to produce chopper and vibration sound. Checked the tracking force and balance of the TT and they are ok. Run my amps on my Spotify feed at high volume and it's ok. Checked table vibration and it's ok.  I am stuck and don't know we're to start. Any help out their will be greatly appreciated. 
mario2016
@  yogiboy ,Yes I do. I will test this tomorrow. May I ask why dustcover will give acaustical feedback?
@mario2016 , Feedback can go right up through the dustcover. You can also turn down the bass control on the Yamaha and see if that works!
Yes the selector is on MM. how far speakers need to be separated from the TT? Aside from the dust covert rial.  I will try to turn off or unplugged the subs. The subs have automatic on upon signal but running at 0 volume.