The Good: The Ikea Symfonisk Bookshelf is a versatile Wi-Fi speaker with perfectly acceptable sound for the price. A pair of them makes the ideal rear speakers for Sonos Beam, Playbar or Playbase sound bars. It's compatible with Sonos multiroom speakers, Apple AirPlay 2, Spotify Connect and third-party music apps as well as Sonos' music app. The Bad: The sound isn't as good as the Sonos One, even when combined as a stereo pair. The bracket that makes it a shelf isn't included. The Bottom Line: The Ikea Symfonisk Bookshelf offers an excellent, affordable introduction to multiroom music and is at its best when used as rears for a Sonos sound bar. Ikea is known for functional, affordable furniture. Sonos is known for easy-to-use, but not necessarily affordable, wireless multiroom speakers. In the Symfonisk Bookshelf the twain shall meet, and the result is the lowest price on a Sonos-compatible Wi-Fi speaker yet. And it also sounds good as anybody can expect for a $99 (\u00a399) speaker.No, it's not nearly as cool as the $179 (\u00a3150) Ikea Symfonisk Table Lamp, which combines a speaker with an attractive, functional light fixture. The Bookshelf is simply a versatile multiroom Wi-Fi speaker that offers similar levels of Sonos-based utility, while cutting the price in half.The Bookshelf sounds very similar to the Lamp, though with less bass, and its price makes it a great option for a kid's system or paired as set of rears for the Sonos Beam, Playbar or Playbase. It takes the Sonos ecosystem to a place it's never been before: multiroom music for less than $100.(Bass) note to shelfThe Symfonisk Bookshelf is not shaped like your typical powered speaker. It's tall and thin instead of squat, measuring a foot tall, 4 inches wide and 6 inches deep. It includes a removable woolen grille that hides a single mid-bass driver and a soft-dome tweeter. The front hosts physical Play and Volume buttons while the rear only offers a backup Ethernet port, in case you don't want to use Wi-Fi.The Symfonisk is designed to be mounted on the wall, that's where the "shelf" part comes in -- the speaker itself is able to hold up to 6.6 pounds. Its rubber grommets on the outside help reduce vibration and stop things you put on it from sliding off. The wall-mount bracket allowing it to function as a shelf isn't included in the box, instead it's available as a $20 extra.The Symfonisk Bookshelf is fully compatible with the Sonos multiroom system, and like other Sonos products it doesn't have Bluetooth streaming. It can be controlled either with the Sonos app, a third-party streaming service such as Spotify Connect, or with a voice assistant such as Amazon Alexa, Google Assistant or Apple's Siri. Apple AirPlay 2 compatibility means that the Bookshelf could also make an affordable multiroom partner with the Apple HomePod. Like other Sonos speakers, two Bookshelves can be paired in stereo or used as rears for the Sonos Beam.The Bookshelf lacks an onboard microphone, which is not surprising for the money, but if you want to make the Symfonisk "smarter" you can add an Echo Dot or Google Home Mini.SetupThe Ikea Symfonisk is compatible with the Sonos Trueplay calibration system, but depending on your room the results may vary. Thankfully if you don't like the resulting sound the Sonos app offers the ability to toggle Trueplay calibration on and off so you can compare them.I used the Bookshelf in a variety of ways including as a single unit, in stereo and as rears for three different sound bars. While the rear speaker option was the best, the other configurations offered their own charms. Each required its own setup, and each time I had to hold the controls on the front down quite hard, while steadying it with my other hand, to get the speakers to register.