A recticfier in a dc circuit ? I think

I realized now after I click post that I spelled Rectifier wrong in the Post title. Sorry.

So i cracked open a "power supply" for a theatrical communications system (Clearcom PK-7), It has a 30V DC power supply, It supplies power and audio connections to up to 30 beltpack/headset units. This particular piece of equipment is around $300. I need a second one, but the belt pack take a range of dc power from 8V to 13V or something like that.
I had thought to myself why couldn't I simply supply power to the units while connecting audio as well,obviously thats what this PK-7 unit is doing. So I opened it up to see. I am just starting out in getting my electronics education, so I thought I would ask around. Why would you need a rectifier after a DC power supply ? From the power supply pins the circuit heads straight for a W02G rectifier, now I had thought that the purpose of a rectifier was to change AC to DC. From the rectifier there are various connections to 3- 30V capacitors what looks like a voltage regulator, and a series of resistors and other components that look similar but I am unfamiliar with, probably to power the LED on the front.

Any insight, I could snap a photo if needed.
Also in case anyone cares, I did indeed hook a generic power supply i had to a set of XLR's and the packs totally function fine, so I am wondering what the need is for all this circuitry.

Thanks
In advance.

Ben

Hard to say without a picture or schematic, but the diode on the output of the power supply might be there to prevent the beltpack batteries from discharging back through the power supply if the power went out while they were connected. That's my guess.

The belt packs have no batteries they receive power only from this unit, Ill snap a picture of the circuit board its pretty clear where the copper goes.

It could be an idiot diode which protects the circuit if someone connects the power backwards.