My best guess is this:
TRS-to-TS adapter connects the signal equally between the tip and the ring… This way the ring (R) is not FLOATING inside the SPACE exp jack… (which is likely how the SPACE EXP jack handles a ring connection) Instead, it allows the ring to conduct thru the TIP (T) of the adapter for the SPACE to read properly.
If all of this is indeed correct (I dont have one in front of me to test), then cutting and re-wiring a new TS jack to the M-audio would also work.
The wires connected and soldered together as T+R–TIP and keeping S as SLEEVE/GROUND
EDIT: In electronic terms, this converts it from a voltage divider to a variable resistor (“rheostat” config). The Ernie Ball VP Jr is wired as a 25K variable resistor. I just checked.