Specifically, I never did understand the 100W Marshall JCM800 head too well actually...I get it well with clean amps like Twins and I also had a 120W all tube Ampeg at some point, and the JCM900 100W also behaved quite OK, but that 100W 800 series was just insanely loud when it properly opened, it really ripped at the ears even with some protection on, because it just has such a cutting midrange.
Dee
"When life's a biatch, be a horny dog"
Amps: Marshall JVM 410H w/ Plexi Cap mod, Choke Mod & Negative Feedback Removal mod, 4x12", Behringer GMX110, Amplitube 3/StealthPedal
Half a dozen custom built/bastardized guitars all with EMG's, mostly 85's, Ibanez Artwood acoustic & Yamaha SGR bass, Epiphone Prophecy SG, Vox Wah, Pitchblack tuner plus assorted pedals, rack gear etc. for home studio use.