@xtv said in Read psx roms off SD card & USB:

One solution could be splitting this into two subdirectories, like A-J and K-Z, one of them being a symlink to the USB drive.

That would be a simple visual solution to "hide" the separate-location structure. You could also split it on release year or franchise to help hide the fact.

Sure thing. Glad it worked

If you can read them via the terminal, then it's ok.
What happens if you restart Emulationstation, after booting ? Will the games show up ?

You can symlinks some of the (larger) ROM folders to the external storage if you want to use both discs, otherwise you can just run all your ROMs from the external disc - https://retropie.org.uk/docs/Running-ROMs-from-a-USB-drive/.