In addition to what the two said above, let me ask - have you run Audyssey?
I'm curious about your statement that the volume stops at 85. Perhaps you have the volume limiter engaged, although "85" doesn't appear to be one of the options in the manual. In the manual, the volume will either display "0 - 98" or "-79.5dB - 18dB" depending on your choice of an absolute or relative volume display. You can set a volume limit, with options of 60, 70, or 80 (using the first scale, which is what you're using based on your description).
I own the Denon AVR-E400, which is very similar to your 1913 in terms of power rating. Granted, I don't often listen to loud audio, but when I checked it out to see if I thought the power was enough, I thought it was VERY loud and still dynamic when set to 0dB. So, hopefully this is just a setting issue that you can change and be happy.