Willie,
I too am a huge Rush fan, but I run through an old school Ampeg SVT rig, so I didn't really have anything helpful to contribute about running direct sans amp (no pun intended). With any one of my Alembics, or my 4001, I can eek out the Geddy tones up until about GUP's sound. but you have to remember that part of Geddy's sound (in fact most of it) is in his technique. From what I've read, he tends to strike the strings pretty hard with his right hand, which helps to contribute that snarly bite that he gets.
Good luck in your quest.
Ken (TEO)