Subwoofer advice

So looking to add a new component (or 2) to my system (Snell Type D, McCormack .5 or Jolida 502b, Schiit Saga pre, Rega Planet, Dual 1219 TT) and contemplating a sub.  Basement room is 14'w x 30'l x 7.5'h and treated with first reflection points and base traps on front wall.  Interested in the REL T series, either the T7i or T9i.  The Snells have 8" woofers so not sure the T7i at 8" will make a significant difference.  The room might be too big as well.  So it might have to be the T9i at 10".  Looking to supplement clean low end not anything bloated or overbearing.  

Any thoughts greatly appreciated!
3. Best Performance system- Audio Kinesis 4-sub Swarm for $3,000. This option will clearly outperform the other options since it will provide deep, fast, smooth, accurate, highly detailed and dynamic bass that will be perceived as the most effortless, the most natural and the best integrated with your main speakers. It will also be the most convenient option to configure since all settings are made once on the amp/control unit for the 4 subs collectively rather than separately on each individual sub. 

Good luck,
   I've respected your detailed and informative suggestions helping people new to subwoofers by sharing your basic knowledge and your enthusiasm with this system. I'm saddened to read your declarations of, "Best, most, and outperform the other options."    
Sorry m-db, don't get your post.  "saddened"?  Nothing wrong with having an opinion.  I welcome all information, and all opinions, as long as your not a d-bag.
@pkatsuleas --

... Looking to supplement clean low end not anything bloated or overbearing.

If you don’t mind going the DIY-route and being you have a fair amount of space allotted, I’d recommend you build 2 horn subs. My experience with them is this: horn bass doesn’t come any smoother, more articulate, enveloping and effortless, period. You get quality AND quantity in abundance, and the latter is equally important because it leaves you with tons of headroom, which means lower distortion from less cone excursion and in return cleaner bass. The better, and gradual coupling to the air via the horn loading equates into higher efficiency, but not least it has the cone movement excite the air more effectively (compared to a cone that loads the air directly) in a way that has the bass become more palpable/present, enveloping and nuanced - also at lower SPL’s. The only drawback: the physical size of the horns, but if you’re really into the best quality and can manage them, get over it.

Design recommendation: Lilmike’s Cinema F20 with the 15" Dayton RSS390HF-4 driver (currently $190 pr. unit at Parts Express). Make the cabs yourself or have someone do it. MDF will do just fine (certainly as a stationary solution), but plywood is better though more expensive. Get the high-pass filter poster @mcreyn recommends (or a miniDSP), and buy a cheap (but fully sufficient) pro amp like a Crown XLS 1502 (~$425 at All this should come in at approx. $1500 total. Google named horn sub design for more info (where build plans can be had for free), and remember to make two of them, in case.

Seriously, no pair of commercially available pre-build sub solution below $5,000 (or even more) will beat a pair of F20 horn subs in the areas overall bass quality and SPL capabilities down to 20Hz. Some may go lower, but would lack in other, more vital areas. Importantly: substantial SPL capabilities isn’t so much about max. SPL per se, but rather headroom. Headroom is your friend, and a surplus of it will give you totally effortless bass that I’d wager only horns subs can provide (and if you high-pass your mains, as recommend already, it’s all win-win).

Just my $0.02..
Hello pkatsuleas,

     You are correct, all of my posts are just my opinions based on my knowledge and experience unless specifically stated otherwise.
     I don’t consider myself an expert on subs or attaining the best in-room bass response. I would more accurately describe myself as a music and movie lover with a strong interest in high quality equipment that’s capable of playing back both in high fidelity.
     I’ve been enjoying various models of Magnepan speakers for many years and have been attempting, for about the same span of years, to supplement what I perceive as their poor quality of bass power, impact and dynamics (excluding their top models) with various levels of success until I employed the 4-sub distributed bass array (DBA) concept in my room. The Audio Kinesis Debra 4-sub DBA system I now use in my system is by far the best bass system, or combination of subs, that I’ve ever experienced in any of my systems.
     The bass is smooth, fast, powerful, dynamic, detailed, natural, seamlessly integrated with my main speakers and overall what I consider near state of the art bass performance in my room for both music and HT. As I understand the DBA concept, the sota results I achieved through this system can be obtained in virtually any room, with any main speakers and without the need for room treatments or room correction.
     All of the above are the reasons I’m such a 4-sub DBA system fan and highly recommend it on so many posts here ad nauseum. This is the best solution I’m aware of for your situation.
     As I’ve stated, however, I believe you’ll also be able to get very good bass performance in your room using just a pair of properly positioned subs if you only require this at a single listening position in your room and not throughout the entire room.
     You’ve already received many good suggestions on this thread for high quality pairs of subs you could use. I thought phusis’s suggestion of DIY horn subs was the most interesting. I’ve read good reviews on these but have never personally heard a pair.

Best of luck,