For muisc get a sub that is fats and pitch accurate.REL.Martin Logan Decent and my budget fave the Vandersteen 2Wq all have multiple drivers to equak the sqaure inch output of 12 to 18 inch single sub with big plodding drivers.Only subes zi know of fast enough and with proper pitch accuracy to blend with nopriously difficult (because of their purity of resolution and speed).Big subs are fine for HT where slam and "Boom In The Room " are most important citeria.Muic subs can be fast and big but I find they start listinbg at aroung $3K like Revel,Great new Velodyne DD series,Arial,Thiel etc.But budget king Vandersteen costs like 41300 jnew $750-800 new and have a very interesting x-over which means you should not use dedicated RCA/XLR cable but use speaker wiores and hook sub at seake level taps and combines with your sattelites at amp (as opposed to feeing through sub and out) because that allows sub to respond to full frequency spectrum not just what is low paased at say 150-hrz.Grteat product with limitations of course.ASt that price you roviding s foundation not going into pipe organ territory or low of heariong.But low note of electric bass is 40Hrz.Better that than some sloppy plodding sub with specs that ar "22 hrx +/- 6Db".Two others low profile VTB (check their site) are fast and muiscal and Infinity top of line subs (part of the MTS Prelude speaker are great iuf you think you might get two (yeah I know your ear can't localize where bass is coming from below 150 hrz so why two subs?Just listyen to a system with two and you'll heasr it.Infintiy subs are thin another easy to live with size wise sub) and has "Rabos System"with Mike and CD-Rom that come with it so you can take out "bass hump" at upperbass region/lower midbass (around 3J\Hrz) taht alomost every roome has.Botht the VTB (also called TBI) Maggelan and Inifinity speakers are great for stereop pair dwon line but so is haveing two of anything.Me I probablywill get two of the 2Wq's if I keep my current speakers $7500 Odeon Tosca's good bass but you can always use a sub unless you are at 20 or 25 hrz and mine are 35 close to Vandersteen low but it will still pressurize room and make a difference.Lokk for SPEED and PITCH accuracy getiung as low as your budget will afford for best MUISICAL results and multi driver designs dliver that in the main thus the REL,Vandy and ML suggestions.
Chazzbo`