Not sure why that is, but I have been told by Sonos rep. tp buy Sonos sub and it will work.
My REL sub work fine now, with only front speakers. My plan was to purchase an Sonos Arc and move my old spekers to to the rear, and reuse my REL sub, but I feel Sonos is forcing me to buy more of their product.
I am closer to ditching the Amp and inverst in new, more friendly set up then spending more $ on additional Sonos product.
Many of us already have third party cmponenets. wich we hsould be able to use with Sonos.
Can anyone suggest alternatives?