Sonos Amp smart amplifier

Sonos brings more power to the just-add-speakers solution from its well-established wireless multiroom ecosystem.

One of the things we like about Sonos is that it doesn’t release iteratively updated new products every year; it uses firmware updates to add new abilities regularly to existing models, and then introduces generational hardware changes when it’s time for something new. And Sonos seems to be having a burst of such creativity at present, having recently announced a musical lamp and musical bookshelf in a cunning collaboration with IKEA (see our last issue), and while Australia waits for those to arrive, there is a new range of architectural speakers (in-wall, in-ceiling and outdoor designs) produced in collaboration with Sonance.

And there is this new Sonos Amp. In many regards the Amp is the most traditional of the new products; the first Sonos product back in 2005 was the ZonePlayer 100 amplifier, which evolved into the Connect:Amp, which the new Amp replaces.

The main role of the new Amp is the same — it contains all the Sonos streaming abilities along with amplification, so that all you need do is plug the speakers of your choice into the back.

But there are three key features which point to the expanded goals of the new model. Firstly, as with the new architectural speakers it has clearly been designed with a major nod to custom installers and integrators who use Sonos in a smart-home environment. Those installers have been using Sonos since its earliest days for both the streaming abilities and the relatively robust behaviour, but the older products weren’t designed to stack or rack-mount. The new Amps sit neatly sit side by side in a rack, and they can stack three high. Their efficient Class-D amplifier technology minimises heat generation but there’s a degree of passive cooling built in, with air intake via their waffle-cut bases, exiting through the indented circle on top, and so their control buttons are shifted from the top and positioned on the front — without,

interestingly, the classic three-button Sonos pad; the three new capacitive buttons (play/pause and contextual volume buttons) are spaced more widely across the front fascia.
A second major change is the inclusion of an HDMI socket. This is less for custom installers, more to give the Amp a second major role as a TV/music hub, just add speakers. Plug in HDMI from your TV’s ARC (Audio Return Channel)-equipped HDMI input for TV audio, use the one RCA line input for another source, and enjoy all the Sonos streaming abilities as well.

The third change is simply the provision of a higher-quality amplifier. This has long been a caveat in our reviews of previous Sonos amps; just not enough power, not enough finesse to enjoy music at its best. Of course there was always the option of using the Connect preamp into a high-quality amplifier. But now Sonos aims to answer that call with an increase to 125W of power from what it describes as a direct-digital feedback amplifier, this term doubling up to describe both the amplifier technology (which seems to be Qualcomm’s DDFA, as used in Bluesound’s original Powernode, see that review), and as a note that the digital inputs aren’t converted to analogue for amplification, but are directly input to the single-chip Class-D amplification.

While there are apparently no optical inputs on the Amp, there’s an optical-to-HDMI converter provided for TVs which don’t have ARC, and we gather adapters are available to convert the analogue input for optical use as well; we’re informed that these cables will sell separately for $39.99.

We first plugged up the Sonos Amp in an emergency, when our reference amp had blown a channel and we had visitors on the way. We had, at the time, our choice of these three smart amps on hand, all requiring networking to their ecosystems, and we took a punt that the Sonos would be fastest at connecting, updating and getting ready for action. And so it proved — remarkably for any networked multiroom-platform device, it was ready to play its streaming sources within five minutes, including a network update.

Not so obvious, however, was the method of changing input (we had our turntable plugged in via our preamp to the line-level rear input). There was no way to do this from the unit’s physical front panel. There’s no physical remote control supplied, neither the supplied literature nor the online user guide seemed to have this information, and it took us an age to hit the right spot on the app (it’s the top left arrow on the Browse screen, and if you’re deep in Spotify or similar you have to back up multiple levels to the first set of options). So quick set-up in one way, less so in another.

But of course Sonos has one of the best developed apps in terms of accessing streaming music. If you have a preferred music service already, you’re almost sure to find it here — Spotify, Deezer, Tidal, Apple Music, Google Play music, TuneIn, iHeartRadio, Mixcloud, Soundcloud, YouTube Music and 59 others were available during our review; once integrated, you can access them quickly via the input selection screen.

One note on Google Play music — we were very impressed that the Sonos implementation of this accesses not only the paid streaming service but also your personal library, if you’ve used Music Manager to upload up to 50,000 tracks Google offers to store/match for free. While playback quality doesn’t come near the original files (and it can take half a lifetime to upload if you have slow speeds and a large obscure collection), once there, it’s both a useful back-up and an access-anywhere version of your favourite music from a browser, but usually unavailable through this kind of app. Bonus.

Voice, AirPlay 2 and Bluetooth
There’s voice integration as well; there’s no mike to listen on the Amp itself, but you can address it from any Amazon Alexa device, and during our review Google Assistant was announced as a further option for US users but not yet Australia. We downloaded the Sonos skills to our Alexa app, and after three days of fails because apparently Alexa compatibility was broken by Sonos introducing Google support in the US, we were helped by Sonos support (which always has an impressively short wait time) to uninstall and reinstall the skills, until Alexa finally found the Amp. Thereafter we were impressed with its ease of use, giving commands to a nearby Echo Dot — no need for magic words, just ‘Alexa play Crowded House in the Den’ , ‘Alexa pause’ (no room required for this), ‘Alexa next song’, ‘Alexa set the volume to 5 (50%) in the Den’. A quick look through the list of commands is enough, and crucially the commands are intuitive and the syntax unstrained. It’s easily the best Alexa control we’ve yet enjoyed.

We tried Siri voice control, which is possible thanks to the inclusion of AirPlay 2, but you can’t say ‘Play music to the Sonos’, or ‘Play music via AirPlay to the Sonos’; you have to manually connect to the Sonos then say something simpler like ‘Play Led Zeppelin’. It’s not quite the dream experience.

Still, AirPlay 2 also enables streaming from any Mac or iOS device with ease, and at CD quality, and including group playback. Roon control also sneaks in via the AirPlay connection. As a final clever AirPlay bonus from Sonos, if you have older Sonos devices which don’t have AirPlay, you can still group them for whole-house playback using one new AirPlay-2 equipped Sonos device receiving from an AirPlay source.

Sonos doesn’t do Bluetooth, and never has. Since Bluetooth offers the lowest of streaming qualities (unless you have aptX or some other proprietary codec at both ends), we’re not criticising that decision, other than to note it removes an easy option for visitors to share music through your system.

So many options; how does it sound? As noted, we had initially set it up to replace our power amps, playing from our preamp plugged into its line input. There’s an impressive setting allowing you to vary the sensitivity of the line input between nine levels, with ‘2’ as the standard AV level of 2V. Despite optimising this, and the Amp’s delivery of perfectly reasonable audio, we were never once grabbed by the music. We checked EQ settings; the ‘loudness’ was selected by default, odd for an amp, so we turned that off, and kept the EQ flat, but still there was a plain-ness to the presentation which assisted neither dynamics nor detail, and failed to deliver the realities of reference hi-fi. When pushed up to rocking levels it would achieve a punchy lively sound, but much further and our ears asked for it to be turned down. This was, we should note, with relatively friendly speakers of high sensitivity. And presumably the analogue input is digitally sampled prior to amplification, so perhaps this stage reduced the quality otherwise available. Yet when we switched to AirPlay to send the files digitally direct from Mac to Amp, the sound was remarkably similar.

We had also been trying to get Sonos to read our iTunes library direct, using the desktop Mac Sonos app to specify the sharing path; it failed once, then took a long time to index the folder (but hey, it’s big). And presto, with the very first track played in that way (an obscure outtake from Roger Waters’ ‘Radio KAOS’), the missing musical magic kicked in, and stayed. Suddenly there seemed headroom and dynamics to the amplification, an openness of tone and warmth of expression to the sound, less distortion preventing higher volumes at pleasure. We time-travelled to classic 1964 Nat King Cole and enjoyed a dreamy Let There be Love, Mr Shearing’s strings soft and sweet, his piano nicely edged in the right channel, Nat’s durry-delicious tones off left of centre. We switched back to the analogue input — same files, different delivery. The direct access through the Sonos app had the edge on everything.

So there’s a lesson: compare your sources. Things were even more radically different when we played the same Nat song from Google play — very quiet, very sludgy, and the vocal and drums central, the strings mono instead of spread, so this seemed a different mix. Spotify delivered this different mix but with less sludginess.

One big gap with Sonos in general is its inability to handle a high-res music collection — Sonos just says no. We were able to add high-res tracks to the Music library, but clicking them just yielded “Encoded at unsupported sample rate 96000Hz”. We got round this by playing non-FLAC non-DSD high-res files in iTunes and AirPlaying them across, and we used the paid solution of Roon to play them via AirPlay. But if you have a high-res music collection, this is a significant negative for Sonos in general.

We really missed having a physical remote control to adjust volume when playing music, particularly through the line input when we weren’t using the app for music selection; opening the app each time is just so much slower and less convenient, and somewhat coarse in control compared to a nudge of a good remote.

This isn’t a problem when watching TV through the Amp. The HDMI ARC input worked impeccably from the ARC-equipped inputs on both our LG and Toshiba TVs, and has the advantage of putting the volume under control of your usual TV remote. (On the other hand it steals one of your TV’s HDMI inputs, of which most TVs are already under-equipped!)

A final bonus comes from the two Ethernet sockets on the back. As on many Sonos products, these can be used for networking other products, even if the Amp itself is connected by Wi-Fi. Sometimes incredibly useful.

The Sonos Amp is most definitely an improvement on the former Connect:Amp in both performance and abilities. That HDMI input sets it up as a lounge hub for TV and music (you can add other Sonos speakers or a second Amp for 4.1 surround), while custom installers will love it all the more given Sonos says you can drive six of its new architectural speakers from one Amp. Has the Amp delivered a real hi-fi experience? At its best, yes, even for critical listening, though we never got transported away as we have been by, say, NAD’s C 338 at $1100, even the $699 integrated amp offerings from Marantz and Yamaha. But then the Sonos Amp is smaller and neater than any of those, with full Sonos streaming. In that regard, and for voice control too, the Amp delivers an impressively upgraded smart solution for both TV and music Sonos systems, and now comes even better equipped for whole-home multiroom music installations. 

Sonos Amp
Price: $999 

+ Part of the Sonos ecosystem with all the streaming options
+ Highly versatile
+ Great improvement sonically on the Connect:Amp

– Analogue input less energetic
– More power but not quite hi-fi
– No remote control, only app
– No Bluetooth, no high-res

Quoted power: 2 x 125W into eight ohms
Inputs: Ethernet/Wi-Fi networking;; HDMI ARC/optical; 1 x RCA analogue/optical (optical adapter not supplied); AirPlay 2
Outputs: speakers out; subwoofer out, Ethernet x 2
Dimensions: 64 x 217 x 217mm
Weight: 2.1kg