Your amp doesn't care much what voltage it gets so long as it is in the range. Get a voltmeter, you may find your generator is putting out 130 volts.
but it is disappointing that you don't see any improvement from the PP. Are you using heavy power cords (10 awg, at least 12) from the wall to the PP and from the PP to the amp?
I use PP10 with excellent results.
Jerry