From what I remember the taller subs will play lower but with less output (not as loud). The middle sized one is usually a good compromise. I haven't heard any of the SVS subs, but I'm trying to go off of memory when I was researching things a few years ago.

Of course, if you're in a small room any output is pretty loud.

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"Nothin' up my sleeve. . ." --Bullwinkle J. Moose