Audio Audio Mixer: Playing clips from the same Group with different Effects

Hello:
I'm getting started with learning about Unity's Audio Mixer. I've got a setup for playing BGM and SFX (each as a separate Group). I want to recreate something similar to the next scenario:

Suppose there are two soldiers shooting at something. One of them is in a clear field, so the gunshots would sound "normal". But another soldier is shooting from behind a waterfall. Let's say we want to apply a Lowpass Effect. The SFX clip would be loaded from a pool, and several of these clips may be played almost at the same time.




The question is: Is there a way to achieve this by using just one Group?

• I've seen MIxer setups where you create a Group for each kind of SFX, but I find that really cumbersome and limited. Besides, that wouldn't help with this problem.
  
• Not sure if Snapshots could work here. A quick Transition may be applied, but many different SFX may change the state before the previous SFX finishes. Unless I'm missing something about how Transitions work.
  
• Using a different Mixer for each case may solve this particular issue, but in my game there will be a lot more

 

I think the only options here are to either:

a) Lowpass the audio source itself directly

b) Use a separate mixer for sounds that should be lowpassed.