Is there a way to set volume on a single event playing instance ( AkPlayingID ) ?

Question

Is it possible to adjust the output volume of a single event playing instance (AkPlayingID) using the API?

One example is collision sounds. The harder the hit the louder we want it to be. 

The only method I have found so far to do this is to have the sound designers set up an RTPC which controls just the volume within their side.

Is there a simpler way to adjust volume on a ANY playing instance using the API? Otherwise, if the RPTC is the way to go, is there a way to create one and attach it to all events in batch?

Thanks!