Take a look at stage photos around '85 and '86. I noticed in 86' that from a live audience point of view he had an outrageously bright, acoustic-ish, sizzly top end. What I noticed was that he was using full range Meyer speakers laying on their sides under the drum riser. Not sure when he went from normal guitar speakers (no tweeters/horns) to these full range things. Do we hear this crispy sound on soundboards too? Live, it was like Bob had his own very powerful PA system. Probably so he could be loud regardless of what Healy wanted of him in the mix. But anyway, there was something to the sound of those full range speakers that really blasted a kazoo, crispy thing out into the crowd. I don't know if he went DI to the PA or what, or if they mic'd the Meyers previously by only mic'ing the 12" and not the horn. Maybe the new '85-'86 sound was the sound of Bob going DI instead of mic'd speaker.
And what about that ADA preamp?? When was that introduced to his rack?
... and it's just like any other day that's ever been...