That's the stock sound. They are highly underrated.
The dude builds them up in a tiny workshop in Dallas. Builds the boards from scratch. I had the one in the video set up with a custom tolex job on the cab. Dave from Naylor had it a week to do it, I think. Gave it a checkup while he had it. He will customize the look and sound to your needs. He's a cool cat to chat with.
I had a SD60 before, and yeah. They're all good. That Naylor sound is right there with Friedman, Bogner and all the good ones for hot-rodded Marshall tone. The feel of the Naylor is unique, I think. Has some bounce and grind, while maintaining clarity. Some folks say the Budda amps are similar to the Naylors. I think there is a Friedman connection for the clean channel of the Duel Naylors, and he helps tweak the Budda Superdrives? Could be wrong about that. Either way, I had both at my house at the same time. The Naylor smoked the Budda. Bigger, more responsive, more open, less compressed sound. But, that was the Budda SD18 compared to a Naylor SD60, so...
I actually bought this amp one from one of the guys in the band that scottosan posted a video of. They all get that sound. Yes, they can do heavy, as well as singing leads and ACDC crunch, not to mention great bluesy sounds. A Perfect Circle, Rick Springfield, George Lynch, Nick Perri, Tim Pierce...all use em for different sounds.