Yes, wireless speakers and headphones are cheaper and better than ever before. But if you want to retrofit an existing stereo system or old boom box to be wireless compatible, the Logitech Bluetooth Music Receiver is just the ticket. This little box makes anything with an auxiliary line-in -- including any old set of PC speakers -- Bluetooth compatible, so you can stream audio from pretty much any smartphone, tablet or Mac -- any many PCs, too. Best of all it retails for as little as $30 (£30, AU$55).
This model is the second generation of Logitech's popular wireless streaming accessory. The new one is smaller than the first version so it's easy to hide behind a receiver or a speaker, since Bluetooth doesn't need line of sight with the source to operate. Like the original, the device draws power from a wall adapter that plugs into the back.
The rear also has a 3.5mm port and RCA jacks to output audio, and the box includes a 3.5mm-to-RCA cable so you can run it in whichever direction you want depending on the audio source in use. The convenience of this system is its flexibility -- you can hook it up to anything with a free input, including a stereo, AV receiver, TV or PC speakers.
Once you wire the adapter to an input, all you have to do is link it to your Bluetooth-enabled device via the pairing button on top. Press it once to put it in pairing mode, then simply click on the adapter in your device's Bluetooth settings menu to connect. Your speakers should emit an audible jingle to let you know the pairing is successful, and that's it. You can even connect two devices at once so you don't have to keep switching them on and off, but only one source will play audio at a time.
According to Logitech, the range of the Bluetooth connection is 50 feet (15 meters). I was actually able to walk a little farther than that in my apartment without dropping the connection, but your mileage may vary depending on other devices you have in the same room, the thickness of your walls and so forth. But like nearly any Bluetooth device, you'll still get occasional wireless hiccups and dropouts.