I'm pretty sure my LTS's CPU had "A64" (or possibly "A64-H") on it, not "R18", but I've attached a heatsink to it now, so I can't check just by looking at it. I guess the information might be accessible via software, but I can't immediately see where.
Also, my board does have a microSD card slot, but it's under the board, where the pluggable eMMC socket is on top. The power jack is a barrel socket, with 3.5 mm outer diameter.
I tried the .dts file and amixer commands in this comment
but still didn't get any audio coming out of my headphones.
I'm willing to help, but I don't have much experience with .dts files or amixer; and, as you may have guessed by now, I can't promise to respond quickly.