Wireless Multiroom Speaker Reviews

Performance
Features
Build Quality
Ergonomics
Value

AT A GLANCE
Plus
Stupendous build quality
Dead-waking dynamics from a single box
Balanced, audiophile-quality sound
Minus
Limited bass extension
Narrow soundstage
Pricey

THE VERDICT
Though it doesn’t come cheap, Naim’s newly revised Mu-so brings true audiophile sensibilities and surprising wallop to a well thought-out and full-featured wireless speaker.

The original Mu-so wireless music system released in 2014 was a first in the emerging "lifestyle audio" category—a truly high-end, wireless, multiroom speaker from one of the most respected brands on the planet. I auditioned the Mu-so back then, and what I remember most from the unboxing was its nearly 30-pound heft, and the manly, finned heatsink that ran the width of the back panel and threatened to cut any flesh that wandered too carelessly in its direction. What I recall from using it was the cool Lucite plinth with backlit logo upon which the console rested; the sensuous, tactile spin of the illuminated volume ring; and the smooth, authoritative sound.

Flash ahead to 2019, and it was déjà vu all over again. The second-generation version Mu-so that arrived for review, simply dubbed Mu-so 2, shares essentially the same form as the original (review at soundandvision.com). But it has been updated in so many ways that Naim declares it 95 percent revised. Let's get into it.

The Mu-so 2 is a rectangular box measuring 24.7 x 4.8 x 10.4 inches (WxHxD). Its brushed aluminum case is broken on top only by the control dial/volume ring, which spins effortlessly and endlessly in either direction but affects change only to the defined volume limits. Inside the ring is a capacitive touch panel that, in this new version, has 15 control options—everything from track transport to input selection to five preset buttons that can be programmed to instantly call up favorite Spotify playlists or internet radio stations. Thanks to a new proximity sensor, the unit wakes from standby and exposes the backlit touch buttons with the wave of a hand. The Lucite base remains, and the Naim logo on its edge still glows when the Mu-so 2 is powered on. (It can be dimmed or turned off, along with the light around the volume ring, using the Naim app.) As before, the wavy fabric grille is available in multiple fashion colors besides the default black, including Olive, Terracoatta, and Peacock.

Wired connections are hidden in a recess on the bottom right from which cables egress via the 0.75- inch lift from the plinth, though you'll have to tilt or flip the heavy Mu-so to get in and make connections—a delicate operation for such a heavy product. Along with a receptacle for the power cord, these include an ARC-equipped HDMI port for a TV (new for this update) and both Toslink optical digital and stereo analog (3.5mm) inputs. There's an Ethernet port for a wired network connection as an alternate to Wi-Fi. A USB type-A port on the right side of the cabinet accepts a flash drive with music files on it.

It's entirely possible you won't use any of the wired inputs. One key difference in the new Mu-so 2 is that it uses the same app-driven streaming platform introduced a while back for all of Naim's Uniti streaming amplifiers, including the Uniti Atom we covered in 2018 (review at soundandvision.com). The iOS/Android app provides integrated access to Spotify Connect, Tidal, and internet radio. If those aren't enough, Mu-so 2 also has Apple AirPlay 2 and Chromecast built-in, which allow you to stream from any music service you can play on your iPhone, or a Chromecast-enabled service from any mobile device. UPnP integration connects with networked music servers, and the system is also Roon Ready. Bluetooth version 4.2 is on board if you need to make a quick connection from a handheld.

For multiroom playback, the app gives you the ability to directly join with other Mu-so or Mu-so Qb speakers, as well as other Naim streaming products. You can also link with any compatible Apple AirPlay 2 speakers using Apple Home or the iOS audio interface, or with Chromecast speakers via Google Home. During my evaluation, I booted a Tidal playlist on my iPhone 6 Plus, then used AirPlay 2 to send the same stream simultaneously to the Mu-so 2, an Apple HomePod speaker, a Sonos Beam soundbar, and a Sonos One speaker, all in different rooms of the house. AirPlay 2 and Chromecast further enable the use of Siri or Google Assistant voice commands from mic-equipped smart speakers or other devices.

The Naim app offers a bunch of other thoughtful functions, including direct input selection, a sleep timer, alarms, both input trim and lip sync sliders for all the wired inputs (the latter in case you encounter trouble while connected to a TV), and a choice of styles for the app wallpaper. A Room Compensation function provides EQ to account for placement in front of a backing wall, in a corner, or out in the open. There's also a loudness compensation switch.

If you're too lazy to boot the app, there's a small, thin IR remote that provides basic volume and transport functions and input selection. And if you lose that in the couch cushions (likely), there's always the touch panel, which was easy to use once I learned what the symbols represented. Naim's quick start guide gave a pretty good lay of the land, and their interactive online support platform provided detailed instructions.

Most of the real updates have happened inside the Mu-so 2. Similar to Mu-so version 1, Mu-so 2 has six drivers across the front: a midrange and tweeter for each of its stereo channels, and a pair of woofers that receive a mono-summed signal. The baffle has been stiffened in this model and its chamfer adjusted to further reduce reflections and refractions that can cause comb filtering. The new drivers were revised by sister company Focal; there's a 5 x 2.5-inch racetrack woofer made of doped-paper pulp, a 2.25-inch cone midrange of the same material, and a 1-inch silk dome tweeter. The woofer's magnet is now 18 percent larger than the original and has a longer, overhung voice-coil to take advantage of an internal redesign that increased cabinet volume for the ported system by 13 percent, with the end result being more powerful and controlled bass. The updated midrange has been given a Tuned Mass Damper (TMD) surround, technology borrowed from Focal's high-end speakers that controls resonances at the outer edge of the cone to deliver a clearer mid-band. The class-D amplifiers—six of them delivering 75 watts RMS to each driver for a substantial 450 watts total—have been carried over from the original.

What else does it have? Well, there's upgraded Wi-Fi (802.11ac; 2.4 or 5 gigahertz) that allows the system to wirelessly stream up to 24-bit/384 kHz hi-res audio, up from just 24-bit/48 kHz in the original Mu-so. Playback support for DSD files is also on board. Then, there's the extra horsepower for the unit's DSP chip, which went from a single-core 150 MIPS (million instructions per second) model to a multi-core, 2,000 MIPS device. This facilitates a much higher degree of fine-tuning for digital crossovers, equalization, compression, and time-alignment. The digital filters are running at a much higher sampling rate now for improved fidelity, and a revised limiting scheme for the woofers helps keep the Mu-so 2 distortion-free even while playing at a very loud volume. I'll be saying more about that, but trust me—it works.

The price of all this tech? $1,599 list.

Setup
I initially placed the Mu-so 2 in my listening studio on a low chest beneath my projection screen about 10 feet from my chair. The Naim app found the speaker quickly and joined it to the network without a hitch. After that, it was just a matter of signing into my Tidal account; Spotify Connect was already active in the app. My chosen speaker location is a good distance from my router upstairs and has presented a challenge for some wireless speakers in the past, so when I noticed in day-to-day use that the app was sometimes failing to find the Mu-so 2 upon boot-up, I availed myself of a wired network connection. Be advised that, even with its Wi-Fi update, Mu-so 2 likes a robust signal.