These sit in different price classes - Sonos Five costs roughly 2.4x what PSB Alpha AM3 does. Expect it to lead on paper; the question is whether the gap is audible enough in your room to be worth it.
| Area | Better | Why |
|---|
| Connections | B | Sonos Five adds Wi-Fi and streaming; PSB Alpha AM3 adds Bluetooth, phono and digital inputs. |
| Size | depends | PSB Alpha AM3 is easier to place; Sonos Five is bigger, which usually goes with fuller bass. Your room decides. |
| Expandability | A | Sonos Five: a sub output. |
| Price | B | PSB Alpha AM3 is cheaper - $449 against $1,098, about 59% less; arguably a different class. |
A Sonos Five B PSB Alpha AM3
depends neither is better in the abstract - it turns on your room, your system or how you will use them. Only specs published for both speakers are judged; anything missing on either side is left out rather than guessed.
Which should you choose?
Neither runs away with it - they trade advantages. Let the "depends" rows and your own room settle it. In a large or open-plan room, Sonos Five has the cabinet volume to fill it more easily; in a small room, near a wall or at desk distance, PSB Alpha AM3 is the easier speaker to get right. Think about the whole system, not just the speakers: the roughly $649 saved by taking the cheaper pair would buy a subwoofer or a better amplifier, and either usually does more for the sound than the difference between these two.
And remember what a spec sheet cannot show: how each looks in your room and whether the finish suits it, what dealer support and warranty are like where you live, and how they actually sound to you. If you can hear them first - ideally with your own music - that will tell you more than any number above.