My understanding is that it is AB with class H Rails, technically, but the claim has been made by the manufacturer.
"The
AHB2 is powerful, compact, cool running and passively cooled (no fans). On the basis of these characteristics, the
AHB2 resembles many class-D switching amplifiers. But make no mistake, the
AHB2 is not a class-D amplifier!
The AHB2 is a linear class-H amplifier with bipolar output transistors and a unique feedforward error-correction system."
High-Resolution Audio Power Amplifiers
benchmarkmedia.com