Do subwoofer pre outs deliver a full range signal? My amp has 12 db crossover (would prefer 18 or 24 db for Low Pass). I'm trying to limit the frequencies my bridged rear channels will need to reproduce. Or is this much ado about nothing?

 

Only some cd players have a full range preout on the sub channels. For example the old Eclipse models did. Most of the new equipment has built in crossovers on the head units for the front / rear and sub preouts. Check with the manufacturer to see if they are defeatable or not as some brands / models may be.

The 12 db slope in your amp is 99.99% of the time more than enough to take care of the range of frequencies played to most speakers. by the sounds of it you have a amp bridged mono to run a couple of subs. If this is the case you are probably fine.

 

My HU has 3 full range 4V pre-outs. Has on-board 5-Band EQ and selectable 6 dB, 12 dB, 18 dB, or 24 dB crossovers with 'bandpassing' abilities (HP and LP and one speaker)

I cross my subs over at 80 Hz with a 12 dB slope. Every system sounds different, so you will just have to play around with it till you get it set the way it sounds the best to you.

 

Speakerman, (or anyone) if you use the head unit 12db low pass slope at 80 Hz do you also use the low pass crossover that I assume your amp has? If so do you use it at 80Hz? I'm wondering if their is a compound effect if you have both a head unit and amplifier crossover? For example, a 12db low pass head unit AND 12 db low pass amplifier crossover both at 80Hz would that essentially create a 24db slope?