Without getting involved in the sealed vs ported argument, despite having owned capable subs of both design types.....I recently purchased an eD A7s-450 with the free eQ.2 (good friend has a pro-audio RTA he's gonna let me use.
. I came from a Hsu VTF-2 and eD A2-300 (both ported). I really enjoyed the sound of all of these subs and went to the large sealed design because of its ability to be EQ'd pretty drastically and still not go destruct-O on me when I watch Terminator Salvation or some other bass heavy movie.
I'm very happy with the A7s-450 but I am even happier with the eD customer service. I cannot and will not speak for any other members here, but my customer service experience has been extremely positive. I have dealt with many audio companies and I would actually put eD on the level with HSU research (which had the best CS of any company I have EVER dealt with).
As for the sealed vs. ported thing, I think a quality sub from a quality manufacturer will tend to sound accurate regardless of program material. SVS, HSU, eD, etc will make subs that, as long as they are properly sized for the room they are occupying, will sound fantastic. The fact is that ported subs are more efficient and sealed subs are more tolerant of being driven very low and loud. As has been stated, you CANNOT get meaningful output below a sub's port-tuning-frequency without an unrealistic amount of driver excursion. The tuning frequency for a ported sub should really be considered its 'basement'....it's not gonna go much lower without physically damaging the driver, as it becomes almost 100% unloaded and lacks any meaningful resistance to the rear. I've watched a friend lose a bet on this. He owed me a beer and himself a new sub.
Sealed subs are a lot less efficient (if you see a small-boxed sealed sub with a puny amp, avoid it) and require more amplifier power. They, however, have no 'tuning drop-off' to endanger the driver and can be driven very low, depending on which company and model you select. This is not to say that sealed subs have a perfectly flat response...they don't.....they are just very accepting of EQ adjustments. My A7s-450 has already generated amazing output at 10-12Hz in my room with some EQ while still sounding amazing on a huge variety of music.
The conundrum is that unless you are a low-bass-head, a tuned port sub will probably fill your bill better. Properly made ported subs are not 'sloppy' or 'loose' or any other negative adjective. I've found properly designed and built ported and sealed subs to sound substantially similar when properly set-up. The ported subs will do it with less power (and usually cost less per dB, as they are more efficient). BUT, if you crave subsonic bass (i.e. below 20Hz)....a sealed sub is usually the best way to achieve that for the above stated reasons.
A ported sub CAN be tuned for an extremely low frequency (just as low as a sealed sub can reasonably go, in fact). BUT, the tradeoff is that the standard size and design of ported sub loses almost all of its efficiency advantage when it is tuned for much below 14-16Hz. To overcome this, larger drivers and a larger cabinet are required (like 15" or 18", usually) to boost efficiency and overall output. If a balance can be struck between very large drivers, an enormous cabinet, a HUGE amp, and an ultra low port tuning frequency, a monster sub (both in size and in output) can be realized. But we're talking a sub that probably weighs more than the couch ur sitting on and is about as big. For normal people with normal budgets and normal living rooms (and normal wives), the above tradeoffs of efficiency vs. ultra low frequency response are almost inevitable.
SVS PB12-NSD, eD A3-300, and the HSU VTF3 MkIII would all sound amazing in most people's living rooms, creating amazing bass (that DOES go quite low) that has fidelity, quality, and impact. I've heard the SVS and it sounds great. The eD A2-300 I owned sounded great but lacked a small portion of the impact of the SVS. The A3-300 has a driver with almost a full ADDITIONAL inch of excursion more than the A2-300, and a 300 watt RMS amplifier (compared to my A2-300's 200 watt RMS amp)...so I think it would compare favorably with the SVS. The HSU needs no introduction and I have enjoyed listening to it as well. There are many good choices out there...i just have some personal experience with these.
