Will a subwoofer add depth and clarity to my system, or just bass?

Ive just found out the Kef Kube series. For my room, I guess a pair of Kubes 10b should work very well.

It's relatively small (easier to move around to reach the best location), reaches 24 Hz, looks nice on the outside, accepts speaker connection, it costs $600 each and it has good reviews. 

Has anyone tried them?

millercarbon,
    Excellent, I'm glad you've got the room gain factor covered with Duke's help.

Duke,
    I think I might have gotten a bit lucky when I setup my 4 Debra subs in my room. I took all the port plugs out at initial setup with the intention of auditioning the system as all 4 running as ported subs first. If I didn't think it sounded very good, my plan was to plug them all and audition the system again as all 4 running as sealed subs to determine if this performed better. If I wasn't pleased with all subs ported or sealed, I figured I could try various combinations of ported and sealed.
    The reason I think I got a bit lucky is because it sounded almost unbelievably good with the first content my friend and I decided to audition it with, a bluray disc of the movie Fury.  
    The first real test came with a preview of the movie Whiplash on this disc that included a drum solo that sounded so amazingly accurate and lifelike that it actually left my friend and I just looking at each other in stunned disbelief.  
    There was an effortless quality to the bass while at the same time a sense of unlimited capacity to the dynamics which I'd only previously experienced with live music.The quality of the bass, as the tempo of the drum solo began slowly at a normal volume but kept gradually building in tempo and volume, was so pitch and tone perfect, accurate and detailed that there was no hint of betrayal in the solid and stable sound stage illusion that there was a guy expertly playing a full drum kit positioned dead center along my living room's front wall. The only accurate way we were able to describe this high a quality level of reproduction was to call it state of the art.  I've been enjoying the Debra system's sota bass response for about 3 yrs now.  I thought you might find it useful to know that I still have all subs configured as ported, with all in mono and powered by the single Dayton amp with the crossover freq. typically set at 40 Hz,no polarity inverted on any sub and my main speakers (with useful bass only to about 36 Hz) running full-range.  The integration between the deep bass of the Debra system with the upper bass to treble of my  large Magnepan panels is seamless. 
      I know the above may sound like a bunch of hyperbole to many reading this because I would probably be highly skeptical reading this good of a review myself if I didn't hear it for myself. I completely agree with the thought of trying to audition a properly setup DBA (distributed bass array) system prior to buying a complete Audio Kinesis DBA system for $2,800 like I did or building your own custom DBA system like millercarbon is currently doing for possibly less money.
      I could probably write a book about how great the AK Debra system works in my system/room and convince nobody but I could probably also give a brief audition of it and convince anyone.
      Since my intention is just to spread the word to fellow music and ht enthusiasts about how exceptionally well DBAs actually perform, however, I have had some concerns about whether the DBA concept really is effective in virtually any given room. If I recall correctly from reading Earl Geddes's White Paper on this subject, I believe he even uses the phrase "in any given room" but I'm going to recheck just to be certain.   I definitely know it works in my room and fairly certain it also did in the Absolute Sound reviewer's room since his review description linked below of the Swarm DBA system in his room so closely resembles my experiences of the Debra DBA system in my room.

www.theabsolutesound.com/articles/audiokinesis-swarm-subwoofer-system/

     As I think you're aware, I was convinced to buy the Debra system by your colleague James Romeyn's generous offer of a full refund option after a 4 week in-home trial period.  Of course, it didn't take long to not only know I wouldn't be returning it but that I'd never need to buy another sub or bass system in my lifetime.  I now have sota bass response but the Debra is still the only DBA I've ever personally setup and the only DBA I've ever personally even listened to in my system and room or any system and room.
     I prefer to make statements and offer opinions that are accurate, truthful and not exaggerated. I respect the obvious knowledge and experience you and James both possess concerning DBA systems and just have a couple of clarifying questions.    
    Are you or James aware of any DBA systems not performing well in any room or system? 
    Are either of you aware of any DBA systems not integrating well with any particular brand, model or type of speakers?

Thanks,
  Tim

Hello plga,

      I think you may also want to consider the SVS-SB1000 subs that go for $499  each.  I know SVS regularly ships to international destinations and would accept returns from Argentina, even though I know you'd prefer not to bother.  But you would get almost $1,000 back to put towards another pair of small subs like the KEF Kubes just in case they didn't work well for you.  The SB1000 are small (13-1/16"W x 13-1/2"H x 15-5/8"D), have powerful 300 watt class D built-in amps , go down to 24 Hz, weigh 27 pounds and have a 5 year warranty.
     These subs do accept speaker line connections from your amp but you'll get varying opinions on the importance of this to sound quality.  The main idea is the sound qualities of your amp will be imparted on both your main speakers and subs when both are fed signals from the same amp.  I've heard REL subs hooked up via the amp and preamp methods and didn't notice a significant benefit of the speaker line method, but others claim they do and you may be able to notice an improvement, too.
     However, there's also a benefit to connecting the subs via the alternative preamp method.  You could run a single rca cable from each L+R channel output on your preamp to each L+R sub input and then an rca cable from each L+R sub output to each of your L+R inputs on your main amp.  
     Each sub has a built in crossover with a filtered rca line output (fixed at 80Hz, 12 dB/per octave high- pass. This method means the subs would reproduce the bass  at 80 Hz or less (or whatever frequency you set the low pass filter on the sub to from 50 to 150 Hz or less) and your main speakers would be freed up to just reproduce frequencies of 80 Hz and up.  I have heard significant improvements in the sound quality of the main pair of speakers when they're freed up from reproducing any deep bass signals. I believe these sound quality benefits are much more obvious to most people, imho, than the less significant improvements gained by using the high level  speaker line connection method provides.
     There's also another option using line-level rca cables connecting your preamp to the subs that entails running your main speakers full range and adjusting the subs low pass crossover frequency by ear until it sounds best to you.
     The main point being that you have a wide range of hookup methods with the SVS SB1000 subs to experiment with in your system.  This means your probably more likely to find a method that sounds and works best for you.

Tim

Thank you Tim!