Using my electric guitar, I keep running into situations where the mix and loudness levels vary widely form place to place and system to system. I am used to this happening with regular analog gear, but not with the rather annoying difficulties it adds in pd. I run into feedback problems with the guitar or the mic, the mix sounds weak, etc. I just cannot seem to get a good, consistent live sound when using the electric and a live mic .. *sigh*.

What do you guys do for your live set? Do you do some sort of EQ/compression on the final stage before going out the the dac~?
I found this post about the ears response to certain frequencies at different sound pressure levels http://gabesrocklog.blogspot.com/2009/08/eq-or-how-to-turn-down-suck-knob.html. Should I try using these curves on an eq going out?
Does anyone know how commercial software deals with this? It seems to me that Logic, Live, etc must have some sort of input/output compensation that I would need to replicate in order to have a more uniform sound across the board?
Is this just subjective and /or not possible?

Thanks for any ideas ...