Here's my attempt at analyzing the photo ...
I'll take a shot at this with zero inside knowledge of Schiit's designs. I've annotated the photo with the letters to indicate what's what.
a. 1 center-tapped transformer winding (for the HV regulated supply)
b. 4 transformer windings (for the high current supply)
c. 1 transformer winding (for the housekeeping stuff)
d. 1 bridge for the HV supply
e. 2 discrete-regulated HV supplies
f. 8 capacitors in the HV supplies
g. 4 bridges for the high-current supplies
h. 4 capacitors for the high-current supplies
na 2 power diodes (for housekeeping rectification)
i. housekeeping circuit with separate ground plane (not in Jason's list)
k. 2 capacitors for the housekeeping supplies
m. 3 separate regulated supplies for housekeeping functions
(there are no items marked with j and l)
I couldn't find the 2 power diodes for the housekeeping power supplies. Maybe they're underneath the board in that area.
HV = high voltage. You can see the marking on the PCB next to the header labeled "a" that it's +/- 70 V. The HV power supply is in the center of the board, and it's flanked by the two high current supplies on either side. The input signal traces are probably routed on the bottom side of the board that we can't see to the amp input circuitry which is in the middle of either side edges of the board next to the heatsinks.
The custom transformer has several windings that convert 120VAC into lower AC voltages, and these are delivered to the white jacks labeled a, b, and c. Once there, the voltages are rectified and converted to DC by bridge rectifiers (labeled BR on the board), and then regulated more tightly by voltage regulators (e and m). The high current stuff is not regulated. All the regulators look like linear regulators.
And some other interesting items:
n. Three output transistors per phase or complement (NPN, PNP). Mirrored on the other side of the board for the other channel.
o. Probably the drivers for the output transistors, maybe part of the bias circuitry for the output devices, and some part of the Schiit's proprietary amp topology, but these are transistors (usually marked Q on boards)
p. PEMs, which are basically nuts you press into circuit boards or panels so you can attach screws to them. I think this is an interesting feature here, because it seems the board is held onto the case from below. It might make manufacturing or servicing easier. Usually boards are on standoffs and a screw goes down from the top to sandwich the board between the screw head and the stand off.
q. Output relays and what appears to be an output inductor. There appears to be an input relay near the XLR jack, and all these relays are probably controlled by the housekeeping microcontroller.
r. This may be part of the monitoring circuit that measures current, voltage, and other things to feed back to the housekeeping microcontroller
s. An RJ-11 jack (like old-school wired telephone jacks) which is probably a serial port used to program and debug the microcontroller.
t. The housekeeping microcontroller.
It's also interesting to see that Jason and Mike have pretty different drawing styles for their layouts. Two things stand out:
1. Jason uses 45-degree angles on his lines with sharp corners while Mike likes smoothly curving lines. Modern CAD software do either one.
2. Mike thieves his ground planes (the little black dots that are empty voids in the copper plane, cf. the Gen. 5 USB board), which is usually done to make PCB manufacturing more reliable.
These are just educated guesses so please take them with a grain of salt!
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