I'm not exactly sure I follow.
For one, nvenc CQ values do not in any way relate to x264 crf values.
You need to figure out each individual numbers that works for you.

Also, the input codec and used filters have little to not impact on the 
output.

Hardware encoders are worse than software ones at the same bitrate, 
quality wise. That's not a bug, but just how things work and are.



Timo