Best multi-purpose subwoofer


Best multi-purpose subwoofer - meaning it fulfills my pursuit for audiophile 2 channel listening and my home theater needs. I have a large TV room 22x22x8 (LxDxH) with floor standing Von Schweikerts VR4 speakers. Room is used both for dedicated 2 channel listening as well as home theater. Unfortunately the design of the room is not the best as it has glass on one side (leading to the backyard) and laundry room behind (meaning its also the family room). Currently I have a 8 inch NHT SW1 old subwoofer which needs an upgrade. The maximum dimensions I can afford on a subwoofer is  15x18x20 (LxDxH). 
As mentioned I want to be able to connect a High Level Input (for 2 channel) and .LFE for HT - so the subwoofer will need to have both. Grace for dedicated listening as well as power for HT. The only time I would consider a larger subwoofer is if it has wireless capabilities so I can place it anywhere in the room. 
Any suggestions on which subwoofer may work best for me? 
128x128ghulamr
I have a couple of 12" woofer SVS subs and like them.  I think an important consideration is whether you want a ported or sealed box design.  I have the sealed box, and truth be told I bought them because I read this is what was the best for 2 channel use.  My system is 2 channel, but it is also hooked up to my video set up.

Just like purist believe a preamp should not have tone and balance controls, they believe sealed box is the way to go.  But I have to admit nowadays that I wish my preamp had tone and balance controls and MAYBE that my subwoofers were ported, to have that "explosive" quality, now and then.
This can always be tough, as you’ve already noticed. The variables are great when maximizing your ROI and the overall acoustics, not to mention personal tastes and your “ear”.

I’ve owned many subs... But will continue to invest in SVS’s SB-16 Ultras (until the next revolution 😉). Had a tough time between JL Fathoms, but in the end the SVSs put a smile on my face every time I listen to 2-channel or a movie. 

I still have the 3 Martin Logan subs it replaced, but I no longer use them unless no one is home, and I can’t see neighbors cars across the street. 

Enjoy the journey! 
It’s interesting to see so many different opinions. The product reviews online are all over the place too. Right now I am getting a good deal on an Earthquake supernova MKIV 15 inch for $625 and an NHT CS-12 for $500. Just lost a great deal on a REL T9i this morning for $300. I’d like to keep myself under the $600 budget - would have definitely opted for the REL’s. But so far it’s the Earthquake and NHT that I need to decide on. Any suggestions - maybe I wait and don’t get either. Thoughts? 
This might have been mentioned already in one of the previous uber-wordy posts, but one of the cool things about RELs (and Vandys but not sure which others) is the speaker jack output to High Level input resulting in the subs sounding like your amp...otherwise long non balanced cable or, if yer lucky, balanced are the only alternatives, but I prefer the REL solution...besides you get to use Neutric Speakons which are made in Liechtenstein. 
ghulamr,

     It seems like you've decided to go with a single sub in your system.  You'll still be able to get good bass response with a single sub if you're willing to accept just having a single bass sweet spot at your listening seat.
     I'd suggest looking at Monoprice's sub offerings and you could buy 2, or even 4, for about your $600 budget.  These will not go as deep as the Earthquake or NHT but I think having 2 or more 12" subs will give better results than a single 15" sub. 
     Remember, all of these subs are run in mono  and you'll get the dual benefits of cumulative bass output(you'll perceive the bass as more powerful but will not be able to pinpoint where it's coming from) and the reduction of room modes that begins when you have 2 or more subs in a given room (bass will sound smoother and more natural).  Also, neither sub is being over-driven.
     I know in any room, 2 subs will provide better bass performance than 1 sub, 3 better than 2 and 4 will provide exceptional bass response.  I can advise you on proper positioning when using any quantity of subs from 1 to 4 and in between.

    For the optimum positioning of 1 sub in your room, I'd recommend placing the sub at your listening position and play some music with good and repetitive bass.   Then, starting at the front right corner of your room,  slowly walk along the perimeter of your room counter-clockwise until the bass sounds best to you.  When you find this exact spot, place your sub at this position.
     Next, sit at your listening seat and replay the same music.  If the bass sounds just as good to you, then you've successfully positioned your sub.  If it doesn't sound just as good, you can either make small adjustments to the sub's position through trial and error until it does sound good to you or start the process all over again from the beginning. 
     
   Tim