On the right:
All the AC stuff - IEC connector, transformers, power switch
power transformer matrix:
-1 large one for B+ and 2 small ones for filament supply
- terminal strips allow easy switching and adding/subtracting voltages for many circuits, KT88/2A3 PP, 300b or what-have-you SE

On the left:
All the DC stuff - FCUPS (film cap universal power supply), ABS (active bias supply), input filter caps
- FCUPS: all film caps power supply in a package comparable in size to toxic electrolytics.
- electronic choke on board with equivalent 500h allows use as virtual battery supply.
- ABS modules. These lock the bias of each tube so anode current is in perfect balance so no DC goes across the OPT core.

When it's there your ears know it, but words don't seem to be able to describe it-- its the soul of music. We've have playing a build up of the Simple 300B as described in this post.
Some more on the circuit:
This is not "typical 300B" operation and needs a 5K load. Power is around 7w at <3% THD.
The V/I ratio is more like 45 than 300B (250v/40ma scaled up to 350v/60a) and, dare I say it, sounds more like a 45 but with much more heft.
Actually it is a WE Data suggested operating point. WE notes 7w @ 4K load with around 3.3% 2nd HD. With a 3K load you get 8w at 5% THD.
Crank the current up to 80ma into 2.5K and you'll get more traditional 300b sound and 10w Class A1 or more if you drive the grid positive.