The year is 2020. Situation for headphone electronics DIY has never looked more bleak. Whatever you build, some Chinese outfit will be able to built it for cheaper and Schiit will probably do it better than you. An exception is e-stat amps due to reasons outside the scope of this post and big friggen transistor amps. Think balanced Beta22, balanced Dynahi, Bryston BHA-1... Hot and heavy Class-A beasts in speaker amp enclosures which cause a hernia if you stare at them for too long. Beta22 is old and prone to self-destruct if you unplug the phones at the wrong time. Dynahi is old and boring, and I've already built a Dynalo which is almost the same thing. As for BHA-1... I prefer paying the iron price, rather than the gold price for my amps. Why not just take a TOTL opamp, plonk a TOTL buffer and wrap them with NFB? Because it's boring AF and it won't probably be able to play Slayer on Ultra settings. And lately I've been dissatisfied with deep NFB designs. So, wat do? Enter the CFA3! A design conjured up in the cult of Dr. Gilmore a few years ago. A design so complex and sparsely documented that to this day no one has attempted to build this amp. The pitch is simple. The amp consists of two modules: Input stage/phase splitter - provides voltage gain, phase splits SE signals, "just" amplifies DIFF signals. Has no overall negative feedback, works in Class-A. Unity gain buffer amp which provides the actual current drive. Each channel has two, which amplify their own phase of the signal. Employs current feedback, works deeply in Class-A, will ignite your headphones before transitioning to Class-B. For power I'm using a pair of cloned Golden Reference PSU's which should provide a clean bipolar 23VDC with noise under 1uV. Here's the PCB: For enclosing this beast I've chosen a Modushop Dissipante big 2U case. Needless to say I'm not looking forward to metalworking. Designs for both front and back panels are in progress, as I haven't decided on what to use for volume attenuation. A Twisted Pear Joshua Tree would be appropriate, but there might not be enough space for it. I might settle for a decent TKD pot instead. Here's the progress so far after 10h of soldering - Still waiting for knobs and feet from China. And some clarity regarding the attenuator.