Odd subwoofer question.

Since you own SONOS amp, why not try their subwoofer. I am using three of them in different systems and the integration is seamless along with superb bass. Setup and tweaking is easy through SONOS app.

If you wanna go ‘wired’ conventional subwoofer route, my money is on REL for 2-ch  systems. 

If you like tight precise bass you are better off without subwoofers unless you have a lot of money to spend. The only commercial subs I have heard that produce "tight, precise bass" are the Magico Q series subs. To do it totally right you need a digital preamp with bass management and room control. I prefer passive subs with out board amplifiers.

I have a Sonos system in my house and have one of their subs in my exercise room. It is not tight and precise but it does add bass to the system and it integrates with their other equipment nicely. It is also big fun to turn the whole house on, sounds like a big venue. 

rel subs are best used with their high level input, but they do have lfe/rca inputs as well

it would be safe to say any modern rel sub would be plenty fast for any application where the main amp is a sonos amp (provided the user follows instructions and properly integrates it/them)

there are some people who don’t get the integration correct, while others unfortunately struggle with a sort of ’reverse placebo effect’ where they mentally can’t get their mind to get out of the way in allowing themselves to hear and accept that well done, subwoofer-supported bass is ’correct’...

Thanks guys. A couple of thoughts.

To be honest I was hoping something for well under $500. The used market might help.

Not interested in a pair of subwoofers. It is only by my wife's good graces that the speakers are in our living room which is fairly formal. So I might be able to sneak one behind the couch but two would be pushing it.

I could try a used Sonos but was concerned about the SQ. I'm not looking for palpable home theater type stuff. However, if it did not work out for the living room I could stick it in one of the other rooms with Sonos speakers.

@mijostyn said:

If you like tight precise bass you are better off without subwoofers unless you have a lot of money to spend.

I'm guessing this is probably the case and I'm now kind of disinclined to go down this path.

@jjss49 said:

there are some people who don’t get the integration correct, while others unfortunately struggle with a sort of ’reverse placebo effect’ where they mentally can’t get their mind to get out of the way in allowing themselves to hear and accept that well done, subwoofer-supported bass is ’correct’...

You probably just described me perfectly. As is, the 6Ts are pretty good with the right recordings. I'd probably go nuts trying to get things back to sounding the way they do without a sub.

So, thanks guys. All things considered I think I'll leave well enough alone.

I’d strongly encourage you to at least try a sub as the benefits go well beyond adding bass and also greatly enhance imaging, soundstage, and overall sense of space.  The SVS 1000 Pro is only about 13” square and 15” depth, will get you down to an honest 20Hz (-3dB), comes with integration software, and this one available on their Outlet is only $575 with free shipping.  And you get a 45-day trial period so if it doesn’t work out for you (or your wife) you can simply return it with free return shipping.  Just trying to help as I know what a sub can do and think it’s at least worth giving a shot especially when SVS makes it so painless.  They also have great customer support if you ever need help with integration, etc. (probably can’t do much about the wife though).  Ok, that’s all I got and hope you get a chance to at least give a sub a try.  

https://www.svsound.com/products/sb-1000-pro-subwoofer