Oh man Duff is kicking so much ass. He and Jason Newsted were the guys that made playing with a pick ok for me. I am really surprised this video hasn't popped in the conversation yet. http://www.youtube.com/watch?v=BnHNkWyGmFw
Here is a rundown of his (relatively) current gig. http://www.youtube.com/watch?v=ANPhIB3dckE
Last but not least I think I found his tone secret http://www.youtube.com/watch?v=4VN9vdwxw8M
4:41, that looks like a sansamp bddi to me.
Moreover I think his tone at least on the first video is pretty simple. To me the key elements to his tone are the clarity of the solid state amp, the pick and the J bridge pickup. Concernig the EQ having played a GK rig for quite some time to me it seems that he makes extensive use of the Contour knob essentially giving him a middle mid scoop(that was not a typo)
and he then boosts the low mids just a bit to get that punchy low end.
The guitarist in my band has a pretty big Slash complex so it made a lot of sense to go for a Duff inspired tone. However I am not giving myself away the same way he does (He has A LOT of Slash Signature equipment). I play a J with quarterpounds through a SA-450 Markbass and a Mark cab loaded with 10'' drivers and I get as close to Duffs tone as I want to get.
But man other than his awesome rock tone, I think Duff is a great songwriter and a really cool bassist. Sure his lines are simple always so groovy. He is also a really smart guy and hard working guy. I used to read his finance articles and always found them really interesting. I am really happy he is through with all of his substance abuse problems and that he can put so much work out there.
I really hope I didn't sound like a fanboy...