Billandsol, a point you may want to consider is that the input impedance of the balanced input of your sub is only 4000 ohms, which may be too low to be an optimal match for the 660 ohm balanced output impedance of your C12 (depending on how the C12's output impedance varies in the lower part of the frequency range).
The much higher 56K unbalanced input impedance of your sub, in combination with the 330 ohm unbalanced output impedance of the C12, suggests that an unbalanced connection may be well worth trying.
Regards,
-- Al
The much higher 56K unbalanced input impedance of your sub, in combination with the 330 ohm unbalanced output impedance of the C12, suggests that an unbalanced connection may be well worth trying.
Regards,
-- Al