It’s not about speech at all. With surrounds (the pair of Sonos Ones) you’d get …well, surround sounds. Cars behind you, airplanes, people chatting in the background. With the mini sub, you’d be getting a boost to low end sounds, like explosions and the like. It all depends on your preferences, but there is no ‘right’ answer. Sooner or later, you’ll end up with both. 

Thanks....I think you may be right but will probably start with the ones.

On the other side…. Adding a Sub will enhance the mids end treble on the soundbar, because the soundbar doesn’t have to take care of the bass anymore. 

Oh ok...more to think about. Would the sub be too strong in an apartment space.? Although the concrete floor would stop annoying the neighbors?

Thanks for your input.

I have a Sub with an Arc and another Sub with a pair of gen 2 Play:5s.  I live in an apartment with concrete floors.  I don’t get complaints from the neighbours….. but I have the Subs a bit toned-down and don’t turn up the general volume too high.  Unless I know the neighbours are out!

The Sub can still enhance the overall sound without making the walls shake.  I haven’t heard the Sub Mini (obviously) but I think the same comments must hold.

Thanks...useful comments

This YT video probably can help you decide. They will demonstrate the sub mini with most sound bars and also explains why adding a sub gives your soundbar better performance in the mid and treble

However it’s a personal decision only you can make. Like @Airgetlam previously mentioned, in the end you probably end up with both rears and sub. Once you start buying Sonos, you can’t stop. Like an addiction, but in a good and healthy way

Great advice there.. thanks for the link.  Trending to the sub now !