I'm not exactly sure what you mean by that. The PPU1 sends the color information and the priority of the sprite that's to be drawn for the current pixel. And then the PPU2 decides whether to draw the sprite or not, depending on the background and sprite priority.Since you've already got everything tidily broken apart, I'd be casually curious what the inter-PPU bus (holding sprite data) looks like.
Thank you, but I don't have an SD2SNES or similar to run custom code right now. I will just ice the idea for a while now, but it's still good to know.I could make a test ROM that specifically puts two (palette+INIDISP) values that should be the same brightness (at least, closer than 1 part in 256).