No, the Sonos Sub is designed to only be connected to another Sonos device. It’s not a generic subwoofer, unfortunately. 

The Sub will only work with amplified, non-portable Sonos products.

You can use the Sub with passive speakers if they are being powered by a Sonos Amp.

• GuitarSuperstar thanks for writing , you mean to say that , I can use SONOS AMP with B&O speakers and then i can conect to Speaker , please correct me if Sam wrong. 

• And non-portable Sonos products - Beolab 18 speakers form B&O are built in Amplifier or please explain me a little more. 

Thanks 

A Sonos Amp is designed to power PASSIVE speakers, not active speakers. Beolab speakers are ACTIVE speakers.

Beolab 18 is not a Sonos product, so you cannot connect a Sonos Sub to them.

BeoLab 28s will not need a sub for anything but super-loud action-adventure movies.  BeoLab 18s make the Sonos Sub look like a total schlub compared to the BeoLab 19 subwoofer, which will automatically be timed to work with the 18s.  And you can’t just hide it in the closet.  (See below for technical details if you decide to try anyway.)  Sure, BeoLab 19 is outrageously costly at $4500, but you just spent $9500-$11,000 for the 18s.

With regard to the various replies above: You could attach a speaker-level--to--line-level box between a Sonos Amp and the BeoLabs.  (Like one from SoundsHeavenly.com, search for “attenuated convertor kit”.) But should you?  No.  Below, in more detail than you probably care at this point, is why:

The BeoLab 18s have built-in DSP, which adds about 4.4milliseconds of latency to the incoming signal.  BeoLab 28’s are even longer, probably 25 msec (or 100 msec, depending on settings).  Sonos have never published the latency of the 5GHz proprietary “bonding” between the Amp and the Sub.  (Maybe we ought to trust them to auto-delay the main signal when the Sub is bonded, but @Sonos have never published/boasted that, either.)  Your chances of getting it perfectly synchronized are nil, which means out-of-phase bass will boost or even quiet some of the frequencies and not others.  This may not matter to you if you are only using it for theater, where the bangs & booms just have to be big.  But if you are using it for orchestral or even EDM, you’ll likely notice something sounds a little off.  4.4msec in time is only a 1.5-meter distance moving the subwoofer behind the speakers vs. your listening position, but you don’t know if/how-many msec for the Sonos, so you could try shifting the Sub around to see what works best -- which maybe you should do anyway… to hide that hideous subwoofer!  (25 msec is just too far.)  Expect to fiddle if you go this route.  See Geoff Martin’s blog entry if you want further info: http://www.tonmeister.ca/wordpress/2017/12/06/bo-tech-beolab-loudspeakers-and-third-party-systems/