I’m not a fan of amps with so many channels per chassis. If you lose one channel you lose the whole thing assuming you send it off to repair.
Also, those JTRs can soak up some power… not that a monolith can’t handle them to s certain extent, but you should really look carefully at how you set amplification up around your whole rig.
Make certain you have adequate power to all channels, that you don’t have a gain mismatch between amps, and that all amps can be reasonably powered by your AVR by matching output voltage to input sensitivity.
Unless you really just want to turn off all amp channels in the AVR and run it in pre-amp mode, I would recommend taking advantage of your AVR amps and using that to power atmos and rear channels…
So if you did that, you could start with a good 5-channel amp and if you want, add more amp channels as you go.