Inputs:OK, let's talk specifics.
Sources
PC over USB: How many channels? What formats?
Optical input from TV and other consoles: Is this stereo? Or lossy DD 5.1 over optical?
Outputs
How many output channels?
What are you doing with FIR? If you have long linear phase FIR filters this can add large delays which are unsuitable for audio/video applications unless you have the ability to delay video.
Michael
PC over USB: Mostly stereo, sometimes 5.1 PCM for gaming (reduced to 4.0 by windows or my AVR since I only have 4.0)
Optical from TV: PCM stereo, pre-decoded stuff from Nvidia Shield (so also PCM), surround only supports lossy dd 5.1 it seems.
Optical from consoles: ditch that, I noticed PS5 doesn't have optical anymore so the TV would process it.
So here my idea already gets cracks on the surface since I forgot that PS5 doesn't have the output and the LG only outputs stereo PCM, maybe 2.1
Outputs:
8 channels balanced would be ideal for all future purposes, currently needed 4
FIR EQ for room correction, currently done with PC since there's enough power and almost no delay.