I'm not positive but I think many of the posters use an amp modeling tool. I have a Line6 Pod which has 32 different amp emulations. They range from the old Tweed Fenders and VOX AC30's to modern stuff I've never heard of. Plus you can create your own sounds if you want.
It just depends on what sound appeals to you. But if you're trying to get a specific sound that particular player has, you need to find out what kind of equipment they have and go from there. Some of the old-timers (Kirk) can probably tell you who is using what just by listening to a few bars. Or sitting in a few bars. Which ever comes first!
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