No, your AVR is pretty typical. And AVRs generally have pre-outs lower than hi-fi gear or DACs because of their high-gain integrated amps.
And the NC502MP is a pretty high-powered amp with a lower-than-AVR gain, so it's just not an ideal fit.
Now, I suspect that in practice you will see no problem. It will go louder than you want to go, and I suspect that the AVR will manage more than my estimated 2V. Just as Denons manage more than 1.6V in practice, despite the 159mV shown in that diagram.
A lot of people here will be using DACs or other hi-fi gear that can comfortably drive 4V. Gain in the 20-26dB range is conventional in non-AVR devices.
I'm not sure why AVRs ended up with higher-gain amp stages...
Anyway, even a NC252MP should be a power boost, as the power ratings for Hypex-based amps are true per-channel ratings. You can hit that with every channel simultaneously.
The power ratings on that receiver are for 2 channels, and you can be confident that will not be achieved on all channels. They don't have the power supplies to be able to do that.
I believe it's related to the Onkyo TX-RZ50? In which case Amir's tests here may show what it can do. I'll need to read it...
This is a review and detailed measurements of the Onkyo TX-RZ50 9.2 8K THX Certified AV Receiver. It was purchased new by a member and drop shipped to me for testing. It costs US $1,399. Looks like all AVR companies are trying to break the mold of just dual rotary controls to something...
www.audiosciencereview.com