Yes, Sonos Amp and Sonos Sub.

Thanx Kumar. Do you know if the amp will have an active crossover filter to define what goes where..?

Frequencies below the chosen crossover will be sent to just the Sub. You can choose the crossover point to be between 50 and 110 Hz via the Sonos control app.

All i needed to know. Thanx. I would hate to let my B&W Matrix 805 go and this solution makes it possible to keep them.    :-)

I would not add the Sub in a hurry, those are excellent speakers. Or, get the Sub on a test basis and see if it really improves the experience before keeping it.

My problem is both the accesability from other devices, but also the lack of sub-bass. My 805´s are located such that my “sweet-spot” is almost bass-less. My room/WAF doesn´t let it be re-arranged. The solution above allows me to put/place a sub where its needed and where it suits me/and the music. As long as i can wirelessly connect the sub.

Keep in mind that if the Sub isn't placed somewhere in between the two speakers, and if you need to set crossover high enough to get more than just the low bass - crossover of 80hz and above - the integration of Sub with main speakers will suffer. Wireless means it can be placed anywhere, but that isn't a guarantee of good results for music if placement is not “good”. For movies, it does not matter so much, but for music it does.

Not using for movies/TV.

In fact I'm only interested in the deepest bass that my Matrix805 delivers (Im sure) - but gets lost in my big room and i cant hear/feel it. Therefore my crossover won´t be above app. 60-70Hz.

The lower the crossover below 80 hz, the less the placement matters. But you also don't want a hole in the bass delivery by going down too low, and then the placement may come back into the mix. 

The nice thing with Sonos is that playing around with all these changes - other than Sub location of course - are quite easily done via the Sonos control app.