This kind of amplifier has been catching my eye lately. The ingenuity behind it is that the op amp at the left can be a low distortion class A amplifier working very linearly, and the only current draw it's going to see is to correct the distortions of the class B amplifier at the right (granted a good balance between the 100mOhm/10k bridge). The whole idea behind it is not to increase any efficiency levels, as the class A amplifier is going to draw some small amounts of current, but to help eliminate any sort of distortion that the class B amplifier can give off. I'm currently trying to design it with an LM3866 IC as the class B integrated equivalent, and a low distortion discrete class A amplifier working at some 250-300mA idle current. Rarely would the class A amplifier see an opportunity to give off so much current to correct the output, as a perfectly balanced system should ideally work with the class B amp as a current amplifier, and the class A amp as a voltage amp, with only correctional function.
