@mijostyn writes:
"You need a complete 2 way crossover and steep filters available only in the digital domain for the best performance.
The best subwoofers are passive, crossovers and amplifiers are outboard."
I have employed this type of thinking in my main system and really enjoy the efforts of going this route. I have custom built cabinets for my low frequency (subwoofer) drivers, an external electronic (digital) crossover, separate power amps for subs and the mid/hi (main) speakers, etc. Removing low frequency information from your main speakers reaps rewards. The low/mid drivers in your main cabinets really "clean up" by not having to reproduce the fundamentals of kick drum, bass guitar, low synth notes, and low pitches of acoustic instruments, etc. that are found below the crossover point chosen to divide the subs and main mid/high cabinets.
A huge issue is that most people don't really wish to go through the thought processes and expense of getting all this gear together. There are a fair number of people, if not most, I suspect, that just want "plug and play" and don't want to deal with the added external crossover, subwoofer amplifier, correctly choosing and designing a passive cabinet with your chosen cabinet maker, choosing the right sub driver, etc. Essentially, it's a pain in the tail end to get it all right. Hence the popularity of products from REL, SVS, etc.
It's only my opinion (and yours may / probably will be different) that a lot (but not all) of these mass market, more affordable powered subs with DSP are 'colored' to my ear if a lot of eq is used in the pre-programmed DSP section of the sub. Most likely done in order to get extended low frequency response that the box/driver design process could not accomplish naturally.
