The actual numbers are just for the sake of clarifying my question, of course. What I mean is, since each channel in a multi-channel convolution has its own filter, what difference does it make if, given three 2d-arrays of data, one first combines that into a multi-channel input that undergoes a multi-channel convolution, vs. use three separate one channel convolutions?
The "channels" just seem to exist for organizing related inputs conceptually rather than mathematically changing anything. Am I missing something?