IN THEORY
Most LOMC's going into most active phono stages sound best with input impedance at about 25X the internal impedance of the cartridge, + or - 50% depending on the system.
So, if Viridian's figure for your Supex is right, your starting point should be about 87.5 ohms (3.5 x 25).
IN PRACTICE
I believe the nearest input impedance on your FET 10 is 100 ohms, so start there. You'll probably want the 60db gain setting.
Try the other input impedances too and decide for yourself. No setting will damage anything. The one which provides best frequency balance in your system is the one to use. This is one parameter where experimentation is the rule.
Most LOMC's going into most active phono stages sound best with input impedance at about 25X the internal impedance of the cartridge, + or - 50% depending on the system.
So, if Viridian's figure for your Supex is right, your starting point should be about 87.5 ohms (3.5 x 25).
IN PRACTICE
I believe the nearest input impedance on your FET 10 is 100 ohms, so start there. You'll probably want the 60db gain setting.
Try the other input impedances too and decide for yourself. No setting will damage anything. The one which provides best frequency balance in your system is the one to use. This is one parameter where experimentation is the rule.