Going by what little I could find, I think it has no bias at all on output transistors. I have made a few amps like that using discrete parts driven by an op amp and the results are bad. Harsh sound, and some crossover distortion.
According to the data sheet, THD + noise, @1KHz with 25w into 4 ohms is 0.015% with a gain of 3. Quiescent current is between 26 & 35mA. So that doesn't appear to be Class B.
I'm quite certain it works in class AB.
A "regular" Op Amp has 2 or 3 mA idle current; this one has 26 to 35mA specified, well into what a discrete, class AB amp of similar power would use.