Just watched this, thought it was kinda interesting:

Wow, thanks for that. Really eye-opening. I never figured GK as a boutique company until he explained why.

I've had an older 400RB (attached power cable, -10db switch under the input) for over 20 years and ever lacked for volume. It can't be all that different from the 800RBs power section since most folks (here at least) are using the full range 300 watt power section and not biamping.

That amp has sounded great on every cab I've played it through or seen others play it through at PRF events, but it always sounded surprisingly great through the SWR Workingman 4x10 cab that I first bought it with in 2003 for ~$250. Actually that cab sounded great with pretty much any amp as well, and if it hadn't been such a beast to carry and I didn't have a bunch of other cabs I'd have kept it!