Line Driver/Gain knob question

If using a line driver in between the sub-woofer preout from the deck to the Sub amp, is there a recommended part of the signal path to have the RCA gain knob?

Basically should a gain knob for sub signal be before or after the line driver?  Or does it matter?

I would think unless you have multiple sub amps to send signal to, then it would not matter. Just to keep things simple I was planning to place it between the deck and the line driver. Was just wondering if there is any reason or details as to having in one part of the signal path over another.  Thanks.