Two major problems that i am sure you are aware of :) are...
#1.Hard to find AV/Automation icons.
#2.When you do find some its not a whole set and the others don't match.
Because of this i would suggest you take a look at the commercially available icon sets from industry GUI pros. They will have what you need because the set is specifically target towards us.[Link: ntdesignsonline.com][Link: blackmancustoms.com][Link: customcodecrafters.com][Link: guifx.com]
This is a list of free icon sets i have found on the web. All have transparent png versions so you can scale them and use them however you want.[Link: guijaboard.com]
This is a quick-n-dirty set of icons i put together a while back. Its pretty good for personal use but since most of the graphics dont belong to me (or you) i would suggest keeping them off clients remotes and touchpanels.[Link: guijaboard.com]