Detlof comments reminded me that, if your pre has two sets of outputs, use one for the main speakers (full spectrum) and the other for the sub. A passive x-over/filter in the sub will filter out the mids and highs while you retain full frequency without added complications to the signal to the main amp/speakers.
Also, while Detlof's assesment is correct, done right, active x-overs will generally add more than they detract. How much more can be a large variable.
Regards
Jim
Also, while Detlof's assesment is correct, done right, active x-overs will generally add more than they detract. How much more can be a large variable.
Regards
Jim