According to Sonos, the Sub can play down to 25 Hz. How much lower do you want it to go?

Does the music you are listening to have any of the lower frequencies in it? 

I found that most of what I was listening to pre-Sonos, mostly CDs and SACDs, didn’t have much at the low end. I added a DBX Sub-harmonic synthesizer to restore some of what the sound engineers took out. Not an easy option for my current Sonos setup but with different Sonos gear it would still be possible.

https://dbxpro.com/en/products/120a

I guess Sonos could be convinced to add lower frequency response if the consumer pressure is there. Engineers long ago learned the facts of life and if they ignore the marketing dept. they don’t eat.

Anything lower is going to need a lot more heft, power and therefore cost. I doubt a market large enough exists for such an animal.

25hz the Sub does now is pretty good compared to other soundbar subwoofer’s you get from Sonos’ competitors.

To try and go any lower would put Sonos in a market where it doesn’t want to compete, with the like of audiophile equipment like SVS subwoofer’s. It would also raise the price - I mean it would be nice if the Sub went down to like 17hz, but achieving that would most likely require the size of the Sub to increase at least 50% and the price to increase by 100%. And how many Sonos customers would be happy to pay double the already premium asking price for Sonos equipment and due to the size requirements, the product would no longer be considered a portable audio product - the upgraded Sub would weigh something like 50-60 pounds