Sonos’ business model differs from most consumer-electronics companies: It doesn’t rely on planned obsolescence for ongoing revenue. Sonos doesn’t want you to replace the product you bought from them two or three years ago; it wants you to expand your system with new components, to bring music to new rooms in your home. “You liked the speaker you bought for the living room,” the company seems to say, “how about adding a smaller one for the bedroom? Hey, now you can connect a Sonos soundbar to your TV. Need more bass response? Our new subwoofer is just the ticket. Why yes, we do have speakers you can use as surround channels in your home theater.” And so on.