Marantz and Denon claim a 70% output of rated power when running all channels.
Do not confuse this with Multi-channel stereo.
(And pls. Don't use MCS. K? Thx.
)
So, depending on your Mains, and all your Speakers power needs, you should play with a calculator like the famous:
Anyway...
So much of this is about preference and need. Only you can really determine your values. Ordinarily I would have led with this, but we know you a little, and I didn't feel like giving you the full sweat.
I do not need
really need Amps, but I use them. I am going to be 2 Monoblocks short of running my whole rig off Monoblock Amps. The reason is that I want the Headroom to push my Speakers to their fullest potential on those rare occasions I need to. That's it.
Again, you have to determine where your values lie and how you want to proceed.
It is your system and your ducats.