With a Beam, you can only add up to two Subs (one must be a Gen 3) and two rear surround speakers. You cannot add any more speakers to the front channels as the Beam already acts as the center, left front, and right front channels.
Get the Sonos Sub. You won’t regret it. But you could get the Sonos Amp later for your two passive speakers and set them up in another room.
AMP does not support a center speaker -- the system will be 4.1. There is no absolute answer to which arrangement is “best” -- BEAM + SUB or AMP + your speakers and subwoofer. If your speakers image well and are relatively close to the TV, a center channel is redundant. If the front speakers are widely placed or don’t image well, you’ll have a “wider” sound image, but you’ll probably miss the center channel.
Thanks for the replies. I was not aware that the beam took up 3 channels as I have seen the Beam + One SL Pair + Sub referred to as 3.1, though thinking about it now, it makes sense. I will likely go with the Sonos sub though if I were to go the Amp +Dumb Sub set up would there be a way to have the Sub work with the surround sound when the TV is on and have the two dumb speakers kick in when music is playing?
Or if I set up the two dumb speakers + Sub as a separate “room” on the app and had both rooms playing the sound from the tv would the L+R be duplicated in both the dumb speakers and beam? Or would there be a marginal delay that would ruin the sound quality? I do this with my Roam pair sometimes when I am cooking and if you are standing between the two sets of speakers there is something notably off about the sound.
With BEAM+Surrounds+SUB the system is 5.1.
With AMP in the 4.1 configuration the SUB or 3rd party subwoofer is always part of the front array.
In some respects asking about BEAM+AMP+Subwoofer in the front is a trick question.
First: AMP+Subwoofer would be a stereo “Room”. BEAM could be a surround Room if surround speakers were “Bonded” to BEAM. Rooms can be “Grouped”.
Next: When music sources are Grouped, all Rooms will be time aligned. When Rooms are Grouped with the TV, there will be a slight latency (about 35ms) between BEAM and other members of the Group. This means that the AMP driven speakers will be a little “late” and this will be very annoying for most viewers. At the cost of less than optimal lip sync, you could adjust BEAM’s lip sync to compensate for the latency. You can experiment with this by bringing the ROAM’s next to the TV.
Finally: BEAM will handle L-C-R and bass while AMP presents Stereo and moves its bass coverage to the subwoofer. Neither BEAM or AMP will be aware that there is a nearby device attempting to deliver the same audio.
Cheers for the response Buzz! Definitely going to go with the Sonos sub though that has resolved a lot of my curiosity. I think I will get an amp down the line to run the dumb speakers in a separate room.