HO boy!!!
Confusion in the mix!!!
I am with Sabith here. Compressors, eq's, gates, any dynamic type processing should work off of the insert, or, post subgroup or master.
Reverbs, delays, chorus, etc....should use aux sends.
I also do not agree at all with trying to use a compressor as a sort of preamp. The issues with trying this are too many, and complex to explain. But, it won't work effectively at all. And the noise that the compressor would generate trying to boost a signal that much would be noticeable even on crappy PC speakers. Mic pre amp's are designed to increase the gain of a microphone signal without adding too much noise at all. Compressors are not made to do this. They offer a little make up gain to maximize the post compressor level for the next gain stage, but not to boost a signal in excess of 15db.
Ed