The local Fender dealer used to have both almost side-by-side, a Bassman 500 on a Bassman 4x10" & a Rumble 500 on a Rumble 4x10". However, I was only trying them at moderate volume. The difference might be glaring at gig-volume. I used to plug everything into the Bassman when I was trying bass guitars there, but it's gone now & I sufficed with the Studio 40 on the Bassman model. Since then I bought The Studio 40 & they haven't replaced it. They pared down on ALL the expensive stuff, no more U.S. Fenders & no more Bassman. I suppose those took a long time to move.