i was reading an interview with the man in question the other day, and he said a lot of times they don't use amps live, but have speaker cabinets onstage for a visual foil. they plug into Line 6 Pods and then into the PA. Rivers prefers it, as there isn't a lot of volume on the stage so it's better for his singing, but there are speakers so they still look cool. not my cup of tea but there ya go, he's a twat 90% of the time anyway right so what are ya gonna do.
he says they started doing it just after Pinkerton bombed when they were playing bowling alleys and skating rinks and stuff and having an amp was less practical.