Most of the current Sonos speakers can produce stereo on their own.  The only one that doesn’t is the Roam.

That said, a pair of speakers with good separation is always going to sound better than a single speaker producing both audio channels.

My understanding is that the following support stereo playback, when standalone…

• Any Sonos Home Theatre product
• Five / Play:5 (horizontal orientation)
• Move 2
• Era 100
• Era 300

That said, it obviously makes a huge difference if you go onto pair two non-home theatre speakers and have clear left/right channel separation.

I think we need to define ‘stereo’ in this context as two (or more) distinct speakers, carrying a right channel, and a left channel. 

All Sonos speakers can play a stereo signal, whether it is from one ’speaker’ or not. 

I have a Gen 2 Play 5 set horizontal and it plays stereo sound. If you sit in the very small sweet spot you get a decent stereo image, outside that spot it sounds a bit better (to my ears) than the mono sound it plays when vertical.

Comparing it to a set of Play 1s, fairly well positioned there is a huge difference in the stereo effect and the sweet spot is far larger.

My Play 5 is the perfect choice for where it sits, no place for a pair of anything. My stereo paired Play 1s, Play 3s and One SLs are a far better choice for getting the stereo effect in the rooms where they sit.