I've got an idea: (I thing Landau does something like that).
guitar - input of hd500
send - orange ad30tc input
suhr di box between power amp and speakers.
mic on speaker -> 1 channel of mixer
line out di box to return of hd500
some effect in stereo
L&R out of hd500 into 2 channel of mixer panpotted properly.
What do you thnk about it?