More than 55 years as perhaps the first Dead PA was 4x MC240 amps running in mono ( about 85 watts ). all bolted to a sheet of Panzerholtz ( just kidding…it was plywood )… but to paraphrase John Curl who helped develop the Wall of Sound, the Dead loved the sound of tubes but w heavy touring needed the reliability of SS…
About the posters…. meh except for those who wanted one before the gold rush…
Full disclosure i own and enjoy the excellent sonics and amazing durability of a 1961 MC240 many days in the listening year…