Different kinds of product: one is active with its amplifier built in, the other passive and needs one. Judge them on how you want to own the system, not just the specs.
| Area | Better | Why |
|---|
| What you buy | depends | Sonos Five is a complete system - just add a source. B&W 606 also needs an amplifier: more money and another box, but you choose it. |
| Connections | depends | Sonos Five has Wi-Fi and streaming built in. With B&W 606 that all comes from the amplifier you pair it with. |
| Upgrade path | depends | B&W 606 can be re-amped later and outlive several amplifiers; Sonos Five ages as one unit. |
| Size | depends | Sonos Five is easier to place; B&W 606 is bigger, which usually goes with fuller bass. Your room decides. |
| Expandability | depends | Sonos Five: a sub output; B&W 606: bi-amping. |
| Price | B | B&W 606 is cheaper - $899 against $1,098, about 18% less. Speakers only - an amplifier narrows that gap. |
A Sonos Five B B&W 606
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?
Sonos Five suits you if you want one box, ready to play, with nothing else to buy. B&W 606 suits you if you already have an amplifier, want to choose the electronics, or expect to upgrade in stages. Neither is the better speaker in the abstract. In a large or open-plan room, B&W 606 has the cabinet volume to fill it more easily; in a small room, near a wall or at desk distance, Sonos Five is the easier speaker to get right.
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.