I run a sub for home theater and have for many years. A good sub for this application needs to hit REALLY low, think 30 and deeper. I've found little preference, although there IS a difference, between down and forward fire-ing, both will do the trick once it's dialed in to match the rest of the system. My current abode (a rental) has a floating Pergo laminate floor that resonates great with deep, loud bass. Explosions, aircraft flybys, with anything that you *should* feel to get the best immersion from a movie, this flooring is a benefit especially with a downfiring sub. A bit higher on the dial and a forward firing sub does just as well but I've found room placement to become more critical.
A sub in this role is used primarily to produce harmonics you can feel, sound quality is of a lesser importance. I'll return to one of my staple "reference" movies, the great WWII submarine movie, U-571. There are several scenes in this movie that feature multiple depth charges in rapid sequence. I once watched this movie put a Yamaha integrated home theater receiver into protection mode at a store display because we pulled the subwoofer out of the equation and the caps in the Yammy couldn't keep up with the demand when asked to do all the grunt work throughout the audio spectrum. Hence the preference for subwoofers with their own amplification.
That said I know dialing in a sub for music purposes becomes a much finer art form, bordering on the arcane. I've never pulled it off 100% to my own satisfaction but the sealed M&Ks have come closest. I think that running smaller satellites in particular must be a real challenge as there is less room for frequency overlap between them and a given sub and I believe that that overlap is critical to producing a seamless frequency sweep between where the main speakers start rolling off and the subwoofer picks up the slack. Hence my personal preference for a full range speaker that can perform adequately, musically, without the use of a sub. I would personally love to hear a high end sat/sub combination that was correctly dialed in for music.
A sub in this role is used primarily to produce harmonics you can feel, sound quality is of a lesser importance. I'll return to one of my staple "reference" movies, the great WWII submarine movie, U-571. There are several scenes in this movie that feature multiple depth charges in rapid sequence. I once watched this movie put a Yamaha integrated home theater receiver into protection mode at a store display because we pulled the subwoofer out of the equation and the caps in the Yammy couldn't keep up with the demand when asked to do all the grunt work throughout the audio spectrum. Hence the preference for subwoofers with their own amplification.
That said I know dialing in a sub for music purposes becomes a much finer art form, bordering on the arcane. I've never pulled it off 100% to my own satisfaction but the sealed M&Ks have come closest. I think that running smaller satellites in particular must be a real challenge as there is less room for frequency overlap between them and a given sub and I believe that that overlap is critical to producing a seamless frequency sweep between where the main speakers start rolling off and the subwoofer picks up the slack. Hence my personal preference for a full range speaker that can perform adequately, musically, without the use of a sub. I would personally love to hear a high end sat/sub combination that was correctly dialed in for music.