Quote Originally Posted by bfalls
I would recommend powered over passive. I don't know of any receivers which have a powered output for a sub. Connecting a passive sub to a receiver would require connecting your mains via the sub's speaker level inputs, thus sharing the power from the main channels with the sub.

Having a powered sub would reduce the strain on the main channels and free up power for mid and high freq reproduction. Especially if you are considering a sub which can reproduce appreciable levels in the 20Hz-30Hz range which takes a low of power.

Most receiver can't even produce rated output with all channels driven. Adding a sub to the mix would reduce the available power to all channels that much more. Unless you have a flagship receiver weighing 45+lbs (due mostly likely to a larger transformer) and 120+W/ch go with a powered sub. If you're a bass guy who likes bass very low and very loud go with a good powered sub.

If you can't swing the cash for a good powered sub. You can still get decent bass with a lesser one and utilize corner placement. From what I've read, corner placement can increase perceived output by 6 - 9 db.
B, this is not correct. You use the LFE output directly to an amp which amplifies the signal to the speakers. All of my H-PAS subs are passive, and that is how I hook them up

Processor's> LFE output > Audyssey sub EQ > amp to speaker.

I do not think either passive or active subs offer any advantage over the other. I use both types, and get great sound from both types. Calibration and room placement are more important than active or passive.