Adam made reference about how impressed he was with the Rivera gear on the FI sessions in a Guitar World interview (Oct 2019).
"The sounds on the record are very much your signature tonal palette - but expanded and exaggerated in a lot of places. Did you start with your stage amps for the core sounds?
"I used my regular setup with my Marshall Superbass and my Diezel VH4s. The transformer in that Marshall is hand-wound in an old-school way that they don’t really do any more, and the wire used is an old-school type of wire and it has a unique thing to it.
"Joe also brought out so many cool things! I was really blown away by the Rivera stuff; those amps sound amazing and the guys at Rivera are so helpful. I’m kind of scratching my head about moving over to Rivera because I was so impressed with their stuff."
Barresi interview:
What was the starting point for Adam’s guitar tones on the new album?
"His sound is definitely his Les Paul Custom into his main Diezel VH4 and that Marshall Superbass, but like the last record, I also implemented a Bogner Uberschall and a Rivera Knucklehead Reverb or a Knucklehead K Tre as part of the equation.
"I recorded both of Adam’s personal amps to their own track and combined the Bogner and Rivera to a single track, plus we ran a mic’d Leslie cab in stereo the whole time, which gave us a total of five tracks wide of just guitar.
"That was the main dirty sound, but the clean sound varied a lot. Besides cleaning up and dropping the gain on the amps we used for distortion sounds, I used an old Orange, an old Peavey, a new Fryette-made Sound City halfstack, an old Kustom and a Naylor. Adam was really into experimenting with other stuff - guitars included - this time around."
He did use a Tre for a few shows as Stephen said, but it didn't stay. I don't think its as big a player as many believe it is. He's used the Bogner as much but I haven't seen that make the rig either.