I wouldn't worry too much about that 86dB at 20hz number from the sound and vision magazine on the Klipsch. I don't even know how they decided at what frequency to capture the 10% distortion levels because it's different for every sub. The Klipsch is tuned somewhere in the mid low 20hz range from what I can see, and at 20hz the sub would be below its port tune. Anyone familiar with ported designs knows that below port tune there is going to be more distortion. So why did they pick 20hz as the 'bass limit' on the Klipsch? That makes no sense.
Perhaps somebody can clear it up for me.
Unless I'm missing something, that particular statistic is particularly invalid and unhelpful. Consider, the HSU is tuned to 16hz --- they didn't capture its "bass limit" at 13hz (3dB lower than port tune like they did on the Klipsch). The Outlaw was tuned to 16hz as well, yet they captured it's 'bass limit' at 20hz. Why the discrepancy? --- With the Outlaws bass limit being captured above tune - they certainly gave that particular single statistic a little advantage for the Outlaw! It doesn't make sense to me. Why was the bass limit on the Velodyne measured at 25hz on a big ported 15" driver? What I'm saying is if you look at that number solely as it relates to the Klipsch, and judge on that statistic alone you'll miss the bigger picture. Sure the Outlaw and HSU dig deeper -- they are tuned to do so, but I've no idea why they chose a point below port tuning on the Klipsch to measure a max spl at 10% distortion. That's junk data. Any sub will produce much higher distortion at lower SPL's when measured below port tune.
I've measured the Klipsch in a a couple different rooms and in several different positions and it's pretty apparent the port tune is at or around 23-24 hz.
Here are the pair of Klipsch in my brothers room running the Klipsch RW-12D built in depth Eq and unoptimized for his room.
Here are the pair of subs optimized in my room with no external EQ, but optimal sub placement.
Notice something? The Klipsch RW-12D subs are obviously below port tune at 20hz.
At 23hz the subs are at about 95dB on my test and I guarantee you they weren't at their limits. True, I was measuring a pair of these but I was just arbitrarily picking a SPL point to begin measuring well above the noise floor in my room. At the arbitrary point I picked and measured from my listening position 11 or 12 feet away I was hearing zero audible distortion and no port noise on the ominimic sweeps at these levels, and I think they had quite a bit of headroom left. Contrast that with a unit like the Crystal Acoustic TX-12 Sub which had audible port noise at these same levels (granted with a single sub (but expensive $750)).
I'm not suggesting the Klipsch RW-12D is better than the HSU or Outlaw 1 on 1. Those two subs will dig deeper because they are in bigger ported boxes and are tuned deeper. The ability to dig deeper is typically more desirable. However, if you only look at the 20hz at 86dB at 10% distortion number and think the Klipsch is weaksause -- even at the sale price of $300 -- you are missing the boat. The Klipsch will be louder, and by the time you account for the fact you can get 2 for the price of 1 of the HSU or Outlaw subs at the seemingly never ending discount -- then you are really getting quite a bit louder system with the dual Klipsch subs. If your limit isn't strictly $600 there are obviously better options than a pair of Klipsch RW-12Ds for a big room. If your limit is $300 (or $600 for a pair) the Klipsch are a pretty good option IMO.
I think the general consensus recommended so far is correct, that if you have $600 or $700 to spend and have a big room get two Klipsch subs and make use of their greater SPL and higher tune. FULLY REALIZING THAT THESE SUBS WILL STILL HAVE LIMITS. (aside: Don't be one of the guys who has a 10,000 cubic foot room and buys a single Klipsch RW-12D to fill it, decides they aren't happy because it's making port noise when they play five star bass movies and then come back here to complain that the Klipsch sub is no good.....
) YOU UNDER BOUGHT SUBWOOFER FOR YOUR ROOM! I would feel the same way. If you want a wowing experience in a large room you'll need more than a typical 12" subwoofer. Which is why I own a pair of JTR Captivators in a 3500 cubic foot room, and they are quite possibly my favorite purchase I've ever made. If I had a 6,000 cubic foot room I'd own four captivators ---- so on and so forth...
Back to topic --- The reason duals of the Klipsch at $600 rather than a single HSU or Outlaw for $700 is a valid recommendation for a large room is that you won't get to take advantage of the lower tuned SPL of the HSU or Outlaw until you spend a lot more than $600 or $700 anyway in a large room --- that is if you plan to get enough SPL in the low frequencies to make it audible or tactile in your big room. However, if you have a smaller room get a single Outlaw or HSU sub and enjoy the 16hz tunes and tactile feel that accompanies that tune! You'll NEVER get that lower 16hz-20hz stuff with the Klipsch no matter how many you stack. The idea of stacking multiples is that a single sub needs to be able to accomplish your frequency response goals and then you add onto that single with an identical sub bumping the overall capability up 3-6dB. If the single can't produce it (especially in the world of ported subwoofers) multiples won't do it.
Here are the numbers from that Sound and Vision Shootout.
HSU with turbo
Bass limit (Max 10% distortion) 16hz at 83dB
25-62hz at 105dB average
Max Output 109 dB at 50hz
Bass limit (Max 10% distortion) 20hz at 86dB25-62hz at 108dB average -- (highest measured)
Max Output 115 dB at 50hz -- (highest measured)
Outlaw Audio LFM-1EX
Bass limit (Max 10% distortion) 20hz at 96dB
25-62hz at 106dB average
Max Output 109dB at 32hz
Bass limit (Max 10% distortion) 32hz at 102dB
25-62hz at 104dB average
Max Output 110dB at 62hz
Bass limit (Max 10% distortion) 25hz at 91dB
25-62hz - 108dB average
Max Output - 114dB at 62hz