Headphone output volume.

Just found a solution :

Got an old behringer ultra patch pro sitting around did a circuit check and it appears the input jacks are trs.
Switched it to open mode so input to output etc.
Plugged in ts in rear to front, trs to LR16 in front. ( used trs to trs cable in front ).
Sound level now works.
So the patchbay doesn’t cause attenuation.
Could add a resistor inside patchbay to mod circuit.
Save on new cables.!!!