Amplifier (VCA) before filter (VCF) or filter before amplifier?

We've reached a moment where it's important to discuss the flexibility we have with signal flow. So far in parts 1 and 2 of the Learning Modular Synthesis tutorial, I've been placing the amplifier (VCA) before the filter (VCF) in the audio signal chain. There is, of course, a reason why I've chosen to do that. But before I dive into that reason, and any reason you might do the opposite, I must state that within an audio/synthesis/sound design context, neither is incorrect. Sure, you may have a preference of one way over the other, but that doesn't mean there isn't a reason for the other way.

I've chosen to place the filter after the amplifier because amplified signals contain amplified noise. And yes, filters can contain noise too! However, placing the filter after the amplifier facilitates a bit more control over noise. This is consistent with typical telecommunications practices; apply filtering to reduce noise in a signal. But (and this is a big but), we might want that noise in our sound! There are a plethora of filter types and circuits available, every one of them with unique characteristics. Placing the amplifier after a filter can enhance these unique characteristics! 

Conclusion:
Try patching the signal in both configurations. Try different filters. VCV Rack in particular is a great playground for this type of experimentation. Have fun and make discoveries! These processes help you discover your sound.