In a decade of reviewing I have seen implementation of some good ideas; banks of smaller capacitors massed vs. a few larger ones, Power Factor Correction, and bridged integrateds like the Musical Fidelity M6500i that I reviewed for Dagogo.com (Note, such a design outputs speaker voltage and current on ALL speaker posts, so it must be handled carefully with certain types of speakers. I have not done a retrospective on these technologies, so I don't know offhand whether they have been brought back from earlier designs or newly developed. Regardless, they seem to be in vogue now.
Despite these advancements I do not think the larger, heavier and much more costly class A and A/B amps will thrive long term.
Despite these advancements I do not think the larger, heavier and much more costly class A and A/B amps will thrive long term.