So after some digging and opening upping i discovered thanks to the diagrams posted here of the stax srd-7 pro and srd-7/mk2 adapters
that they sport the same pcb.
Even better there are unused holes so theoretically i could just get the corresponding resistors, capacitors and have at it



Notice how it even states N-bias and P-bias right on the board, awesome.
Only question is how can i get the extra plug to work should i replace one of the pro plugs or can i make an extra wire to the outside of the box ?
Did see that the two connectors are paralleled.
Also the middle pin of the normal bias has to be connected to the bottom left pin of the plug ? and then of course connect to the N-Bias connection on the pcb.
I will let you guys know what happens.