Ohhh, so just plugging the power amp and running the front 5 channels would not help the receiver at all?
Like @peng said, the Emo amp doesn't offer better distortion/noise specs than the internal Denon amps. It may add a bit of extra power but not a lot. The only real value of the Emo amp would be to lessen the load of 5 channels on the Denon 4700.
The Denon 4700 full pre-amp mode requires all internal amps to be turned off to produce higher SINAD. Five channels is not enough to drive a 7.2.4 configuration.
You could select to have the Fronts ONLY in pre-out mode but that still leaves all the other channels on. Read the manual on this configuration as it requires one specific amp assign mode to make it work.
All in all, I would try the Denon 4700 without external amps first with the "AC Infinity MULTIFAN S7, Quiet Dual 120mm USB Fan"
and use AUTO ECO mode. It's very possible that will work fine. If you still want external amps later maybe think strategically how many channels you want active, look up their SINAD/Specs to be sure it's an improvement and decide whether it's worth shooting for full pre-out mode.
Bottom line with Denon 4700 is if you want the max. SINAD it requires all internal amps off. But you may not need that at all. So try it alone first so you have a baseline of whether that works for you.