Here are the files for the SAO that I passed out at defcon.
Thank you for reading this document.
As for how this little thing works, there are six resistors that will needed to be added to the board.
You Positive, big input from your amp.
Your negative, little input from your amp.
this is for the connection to the grounding plane, it can be bridged (Zero Ohmes Resistor) or you can drop a resistor here to tweak your sound profile.
This one is for the LED at D1. I was gonna make this blink, in the tradition of all SAO being blinky, but in the OTHER tradition of SAO I got lazy, and just put the pads there.
I am probably distributing these with both the standoffs on (with resistors) and standoffs off (no resistors). You can source all the bits from the schematics and KiCad files. Oh, you will need KiCad 6? I think? That is the version I used to make the files, so your milage may vary with other versions of the software.
This thing comes "as is" with no warrenty, implied or otherwise. Good friggin' luck.
If you have questions, comments, or just need someone to yell at, feel free to drop me a line on the email address on the SAO itself. If you think you can do this better, and come up with a modified file, I would LOVE to see it. I used this whole thing to learn the tools involved, and to not have to deal with switching audio interfaces. Again, inspired by laziness.