Keep going, you are just about ready to use the Denon as a pre-pro altogether. And why not? Denons get hot. You could take it from broiler to bread warmer. Get two more BasX A-500 amps and you will have 13 channels to play with and a second two channel zone for the patio while you grill dogs. Joy!
Or, use the two extra channels to bi-amp the fronts and just boil the hot dogs in the kitchen. I always preferred them that way.
Though, not sure you can assign the Zone 2 or Zone 3 PRE OUTs to Bi-Amp the FRONT channels when in 13.1 Pre- Pro mode.
Just grill the dogs on the patio while listening to Zone 2 and call it good.