I just finished making my first cable! It is for a 2.5mm balanced output from an Onkyo DPX1A, to lemo connectors for a Focal Utopia. I am pretty sure I got it hooked up correctly.
The TRRS is R-, R+, L+, L- respectively.
The Lemo is + on the side with the Red dot. I used an insulation resistance tester to verify there is no insulation issues (or shorting) between any of the connections.
I noticed that the S (of the TRRS) is in electrical connection with the metal shielding on the plug (ie the piece you hold when plugging it in). Could that create a problem (eg static) when I touch it while listening to the headphones using the cable?