2D Sprites in 3D game

I’m trying to make a fan version of the game Bernband and am having some trouble with the sprites I am using.
I’ve using this technique to create a filter on my game, and I’ve imported some pixelated sprites into my game. These sprites are already quite low resolution, which is what I want, but the filter that I am using lowers them even more.
Does anyone have any alternatives or suggestions to help?

Quickest fix I can think of:

Have two cameras, one with the filter(A) and one without(B). Have camera A render everything except the layer of the sprites and camera B render only the layer with the sprites. Make B a child of A and reset it’s transform.