"So should i do it b/w two chassis or on the actual OEM umbilical cable?
Since you are having a "cable" made, you need to take the readings from the OEM cable itself. As long as it is the correct cable anyway.
You could also contact the preamp manufacturer and ask how it is wired.
Since you are having a "cable" made, you need to take the readings from the OEM cable itself. As long as it is the correct cable anyway.
You could also contact the preamp manufacturer and ask how it is wired.