It's still an attenuator, but it also has an 11-band EQ to emulate the various EQ curves of different speaker/mic combos.
They've got a curve shown on their site for a V30/SM57 combo, and one for a GT75 in the manual.
I'd love to hear one; kinda kills two birds with one stone.
Rivera is the shit. Best amp brand out there IMO. I love both my heads, I would love to have one of these.