This is a "current drive" or VCCS class A headphone amplifier. Some advocacy of current drive (as well as a whole book on the topic) can be found at current-drive.info.
The first prototype is briefly described on Prototype page.
The current version of the schematic is showed below.
Two such channels with a dedicated linear PSU are going to be fit into an extruded aluminum enclosure with internal dimensions of 96x155x50 mm.