Hi Martin
? ? ? ? ? ? ? ? ? I suppose for those of us tinkering total waterproofing isn't to much of an issue, I doubt any particular preamp I've built has been outside long enough to rust or rot :)? mind you even after a week or so the condensation you mention is often visible,? ?for Andrew and other manufacturer's it must be a royal pain in the butt.. (I was thinking about Auto electronics as well) I think they pot ECU's as well...
73 Paul