People are spending more than a thousand dollars on these subwoofers that they intend to use for years.
And bass is usually what is most affected by the surrounding environments.
It may sound great in the showroom. But once you get it home and there are no bass traps, expect a very different bass curve (and therefore sound) than what you hear at the showroom. I will never go down to a showroom to hear a subwoofer when it is easily the most affected by the environment resonating with the bass which can cause peaks and dips in some of the frequency ranges.
As an example, the KEF KC62 has built-in EQs meant for the locations that you place your subwoofer in. Room, Corner, Cabinet and so on. The bass frequency sweeps that I did defers wildly between EQs as expected since depending on the placement of your subwoofer and the condition of the room that it is in, the bass will sound a lot worst than it ever has been in a well treated showroom due to how much the room resonates with the bass frequency.
Thus my advice to not just depend on your hearing but also look at the frequency response. They are provided by the companies as a specification of the subwoofer on their own site. There's no need to refer to Reviewers who also give frequency responses though it will really help a lot too. Like buying anything else, we would at least do a bit of research to know what's right for us. And not just depend blindly on salesmen on the stores which are encouraged to move the slow moving and usually, poor performing products, off the store to clueless customers.
It is a shame that such poor advice is passed off to poor unsuspecting customers. And then here, we have them justifying that it's alright to give poor advice to others and in fact, it's much more encouraged than to refer to specifications and features to compare with like with any other product that we usually buy.
My advice was simple. Look at the frequency responses of the subwoofers within your price budget. Make sure they do the full sub bass range and then, you can opt to go down and hear both for yourself and choose which one you like better. It is a lot better than going in blind, listening to marketing as opposed to genuine advice and then being fooled by more than a thousand dollars for a poor performing product. My aim is to not want others to get cheated out of their money.
I am glad users like Vodkilla has benefited from all the factually good advice that has been given by others. I too agree that if you have a subwoofer and you cannot get your room treated, using a Room Correction software which typically does Parametric EQ as opposed to regular EQ where you can't EQ a lot of the frequency range will help substantially. Room Correction software like the ones in your AVR will mathematically try to fix the sound coming out of your speakers to the microphone position which is where your ears are at.
Dirac is one of the best Room Correction softwares on the market. It not only does Parametric EQ but also time alignment and phase correction.
Do you know how the fake snake oil custom speaker cable sellers try to convince you that their cables will improve the sound of your speakers? They play with the cable length of the positive and negative along with the slight difference in length between the right and left speakers. This will have an impact on the time, however minor along with the phase. But, it will be audible to us in the form of how big the soundstage becomes. But this is how they convince you that their ludicrously expensive custom speaker cables will make a huge difference to your speakers.
Don't waste money on that. Concentrate on cable gauges. Seen as AWGs. The lower, the better. But they'll be a lot thicker. But for shorter lengths, it won't matter much since there's less resistance.
As for soundstage, sound quality and so on, I'd rather you invest your money in the best Room Correction softwares like Dirac or Anthem's ARC. So try to get AVRs with them.
They can fix a lot of issues with the room, the soundstage, your speaker imbalance in some of the frequency ranges to the best of its ability via Parametric EQ Correction. If you provide it with the speakers and subwoofer that can do the full range of 20Hz to 130Hz for the subwoofer and 70Hz to 20,000Hz for the speakers with the help of the spec's Frequency Response at ±3 dB, it will greatly help the Room Correction software. Then, you can use the Room Correction software to adjust the frequency curve to your taste.
That's how versatile a Room Correction software is vs buying a physical hardware like a subwoofer with a horrible frequency response that you cannot change the sound curve as much if you do not like how it sounds in your home.
Thus, the best advice that I can give is to research on a speaker that gives as flat of a frequency response graph as much as possible. And then do the same for the subwoofer. And then get an AVR with Dirac like the Denon X3800H or the Marantz Cinema 50. This is the cheapest and most value oriented things that you can buy in the Audio space and get the most out of your audio system.
Without having to buy expensive snake oil cables (Remember, speaker cables are literally just copper wires that is used in almost everything electronic because it is the best and cheapest there is) and other snake oil lidden consumer audio products, a very capable speaker and subwoofer coupled with an AVR with the fantastic Room Correction software can help you tweak the sound signature of the said speakers and subwoofer to suit your taste via Parametric EQ. And you can change the sound signature on the fly. Something that you cannot do with a poor performing speaker or subwoofer with wild spikes in the frequency response graph that the trustworthy reviewers that show you the graphs can provide you with.
Whenever possible, do not listen to subjective reviewers and advices online. Remember, just like in school, our expectations and taste differs wildly from one another. Some are happy to get 50/100. Others expect at least a 90. But the problem is, we can't read their minds and know what their standards are. So anyone can just say this subwoofer greatly improves my audio experience. But we do not know where they were coming from before and whether their taste is the same as yours. Thus, you'll be receiving extremely bad advice not catered to your own standards and taste. Thus, with an objective graph, you'll be able to narrow down what subwoofers meet the criteria of being an actual subwoofer. And then, you can go down and see or maybe hear what they sound like but knowing that whichever you end up with at home, their flatter graph means that you can fix many issues with the subwoofer based on how the room and the things in your room is making the subwoofer sound bloated in some frequency range thanks to having a Room Correction software.
No need to waste money trying to fix issues with your speakers with power cables and so on where you can't predict whether it will improve your audio until you've already bought it and then regretting it when it improves so slightly or even none after that.
You'll save a ton of money that can be used into maybe adding more speakers over time to create a Dolby Atmos or DTS:X setup in the future. And not to mention, having a Home Theatre System that you will be happy with for a very long time. No need to go back to forums trying to ask for more advice on the next best speakers or wires when you already have speakers that are flat and therefore is easier to EQ with the Room Correction software which can fix your room issues long into moving the system to a different room or moving houses or adding newer speakers.
I can tell you this. Armed with the information provided by useful sites like AudioScienceReview and AudioHolics, I bought the Elac Debut 2.0 speakers and they do sound amazing. It became even more amazing thanks to Room Correction software trying to fix any faults in the speakers' sound reproduction. When I replaced the front speakers with the KEF R3 which was rated one of the highest on ASR back then, I became underwhelmed. The improvement was extremely minor. Just a slightly better specular highlight details in the high frequency range. But minor. Everything else sounded the same thanks to Dirac correcting the speaker time, phase and imbalance in the sound reproduction. For the price I paid for the KEF R3s versus the Elac Debut 2.0 speakers, the price to performance is not worth it. But again, this is expected thanks to how much Dirac fixes a lot of issues along with the score of the Elac Debut being high up and close to the more expensive KEF R3s.
Basically, what I am saying is that the objective graphs and objective reviews are in line with my own subjective experience.
For those who are value oriented and wants the best performance for the price, I will recommend the newer and better scoring,
Speakers: Elac Debut Reference series of speakers (it has a flatter frequency response) or the Elac Debut 2.0 (way cheaper now)
Subwoofer: SVS SB-2000 PRO or the SVS SB-1000 PRO if you want a smaller subwoofer (not the one without the 'PRO' model)
AVR Receiver: Denon X3800H or Marantz Cinema 50 (the cheapest AVRs that has Dirac Live Room Correction built-in on the market)
If any of you have any questions, just quote me here and I'll try my best to help. You can even quote our well versed in the audio and video world moderator, petetherock as well. He has pinned threads in this subforum giving you great advice if you wish to know more into detail on Home Theatre Products and what to look out for all things audio and video related. There are many very useful links that he quoted to from credible sources in the audio industry.