I've got a 1968 Harmony 540 speaker cab with four Jensen C10R speakers. Great sounding cab, but being 54 years old shouldn't really be pushed with a lot of wattage. It sounds good with my Excelsior Pro, but not really the sound I'm looking for and all my other amps are 100 watters. I've played on a pals Classic 30 and I think the 20 just may be the ticket for this old cab. Any opinions?