Hi Os
That looks like a triple with the driver stage biased to the rails. It does show improved figures, scheme used by electrocompaniet and some others. Electrocompaniet goes further and uses a current source instead of resistors to bias which improves things further if youd like to try. Adreia Scafolli a Italian designer goes even further and biases the predrivers like that too, all show improvements THD wise, as for the sound youd have to try and listen to the sound of these schemes. The one you showed but using current sources gives a mighty kick in the bass but your amp better be quite fast or the bass will overwhelm. Carlos the destroyer didnt like it, I found no problems with it except the rest of the amp should be fast or the mids will sound slightly muddled.
