Repurpose my AVR for multichannel use - A little guidance appreciated

Greetings people

As title suggests, I am currently scheming to repurpose my Yamaha RX-V1700, and would very much appreciate some feedback before I move forward, in case I have missed something. The plan was for pure multichannel amp use for DIY 4-way active speakers. I will use external DAC to multichannel input to 6 of the amp-channels and 2 preouts (center and SW) for volume controlled pass-through. AVR will not be used for other duties after this.

So as known AVR's have some internal stuff going on in regards to LFE/SW. My plan is to change components in SW preamp channel to mimmic the other descrete inputs. This will consist of removing the SW mix with main L and R, removing/bypassing LP filter and changing components to get the same gain structure in preamp circuit as rest of the channels.

Here are some shots from the diagram where I've found need work:
Multichannel input
Input.JPG

LP filter
SW multich. input.JPG

Pre volume control
SW gain prevol.JPG

Post volume control
SW gain postvol.JPG

Pre-out SW and Center
Preout.JPG


If anyone has some thoughts or advice if my plan seems ok, or if I have missed something feedback is most welcome
 
So after some more thinking, something that should be very obvious by looking at the gain scheme is that the digital volume control has different gain for sub channel. Silly me thought the volume control chip did all channels equal, but no....
I have been looking at the datasheet for the YAC523 chip, and seems like an interresting device. Seems like my plan is more complicated than needed
 
Finally found the time to start some mods. I did some measurements to see the the effects of LP filter on sub signal path. LP filtering happens in two steps, the one I posted as LP, but also an additional in the pre-out. I bypassed the LP filter and changed some cap values.
Here are RTA measurements before and after. At this time I will use speaker level adjust in AVR meny to get LFE channel gain equal to the rest. I have some ideas for more mods, but that will be for another time
Sub pre out.PNG
Sub pre out LP filter removed.PNG

Nice and straight FR after mod