Note: Pricing for this product is in US$.

If you already have a multi-room digital music-streaming system, you don't have to replace it, but the Zone Player 120 is a nice choice for new buyers.

In early 2005 Sonos introduced the basic building block of its multi-room digital music system: the ZonePlayer 100, a combination digital music streamer and amplifier. Since that time, the ZP100 has gained lots of new capabilities through software updates, but the hardware itself didn't change. Now, more than three years later, Sonos has finally released a new version, the Zone Player 120. Although that gap is an eon in technology years, don't expect huge differences in the new box.

Zone Players are the heart of the Sonos system. You place them anywhere in your house where you want to hear music. Add the company's CR100, a handheld controller designed a bit like an iPod, and you can play music in all the zones of your house — either the same music everywhere or different tracks in different rooms. The various pieces of Sonos hardware communicate among themselves through a wireless mesh network that the devices automatically set up. A basic two-zone system costs $999.

(Earlier this year, Logitech released a less expensive alternative, called the Squeezebox Duet; a comparable two-zone setup with the Duet costs $550. But its streaming devices don't include an amplifier — they have to be connected to your stereo or to powered speakers.)

The new Zone Player 120 is 35 percent smaller than the ZP100, thanks to an extruded aluminium case that acts as a heat sink. (Sonos doesn't use any fans to cool inside; I didn't feel the unit get hot to the touch, however.)

The company also claims that it has doubled the wireless range in the ZP120. Reliably testing wireless range is difficult because of interference from other wireless sources or because of obstruction by walls and windows, but I did find that I could use the system in the far reaches of my house, something that was occasionally a problem with the older Sonos hardware.

The ZP120 also boasts more audio power, 55 watts per channel, up from 50 watts per channel in the older version.

In addition to the ZP120, Sonos has refreshed its ZP80, a zone player without a built-in amplifier that you can plug into your existing stereo system. The $349 ZP90 is the same size as the original, but also boasts improved wireless range, according to Sonos.