Yep, A/B would be best...but of course somehow incorporating everything into one chassis would be simple.
But, it's true...attenuators & big tube amps aren't a very good combination at least in long run. Perhaps just a little attenuation would work, though...just a few dB would do I think.
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.