I was watching the Hendrix at Berkeley dvd the other day, and there was a close up shot showing his rig, showing him plugged into the NORMAL channel of his head, daisychained to the normal side of the second head!
God damn- I wish I'd seen that thirty years ago- I've been wrestling with the tone of my strat through the bright channel in Marshalls since 1970!
so THAT'S how he did it!
(Oh, and maybe a bit of voodoo...)
-Pete