IIRC, indeed, back in 2003 when I was thinking to do such a connector I couldn't get the signals due to the chip on the PSX pads "mobo".
So I left the PSX2Amy pad as an idea only, and "hacked" some Sega pad by connecting the Amy cable directly to the pad's "mobo".
Now I have a spare broken console, so maybe I'll try that with the double-pad-connector-thingy from that one...
Thanks for reviving the idea, Cammy
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Nah, impossible, there must be a chip there somewhere, here's what signals appear on the pad's port