Review and Measurements of SONOS Amp

[hyfynut]

I praised such detail when I commented on the nice feel of the power cord. I question the management decision to spend a lot of money on that, when they could have better engineered the core product. It is a sign of a company not using its resources wisely.

This is a company I have known since inception since my team at Microsoft worked with them to implement our audio formats in their products. We used to hold them up as a great example of how to do computer audio right when talking to just about any small and large audio company. It is under that light that I critique where they have landed where they missed the most important innovation in streaming content to a speaker at home.

When I look at this amplifier and its software, little of that excitement is there anymore that existed when I looked at their first generation product with that very nice, flashy controller.

When I lived in silicon valley, the moment we saw a company started to construct fancy buildings instead of putting the money towards product development, we would joke that their stock would tank and in almost every case they did! Same here. When I look at attention put in a power cord instead of internal design, features and usability of software, I worry about the company.

I have to disagree completely with your criticism of the power cord they are using. They are using this same power cord in many of their products so economy of scale would make it cost effective rather than an overpriced embelishment.
How did the unit perform while streaming audio ? I skimmed the review but must have missed that part.

 

[Darwin]

I have to disagree completely with your criticism of the power cord they are using. They are using this same power cord in many of their products so economy of scale would make it cost effective rather than an overpriced embelishment.
How did the unit perform while streaming audio ? I skimmed the review but must have missed that part.

Yeah I don’t get the complaint. I like the thought that went into making things look and feel nice.

 

[Darwin]

That amp is waaaay overpriced and we may do better with a Rasberry PI hack plus an audio hat, a PI that may receive a wifi-based stream from a Linux implementation of airplay. Sonos streaming architecture is proprietary and what they have that we would have a hard time implementing are ways to keep all the sinks in sync. Data communication, real-time streaming is what I do for a living and I would like to try doing what Sonos does, but with several Raspberry PIs with amp hats on them, receiving audio streams from a server-PI. PI running Linux, coded in Golang RTC.

I buy my B&W speakers at a shop that also sells Sonos. While there I spend some time listening to their Sonos, blue sound, Dali, etc. Last week I listened to Sonos Beam Gen 2 and Sonos One Gen 2 speakers. They sell really well according to staff and I agree that their active speakers seem very convenient for those who just want to spread out speakers here and there and listen without efforts in connectin them. The sound from those speakers however is boxy and boomy with poor midrange and I can't stand listening to them.
We can do much better,,,,

I am very technical but your solution is way too much trouble and way too messy for me. You pay for convenience with the amp and other Sonos products and I’m happy to do it. I’ve done all the roll your own and higher priced components and passive speakers and Sonos is built for streaming and so easy. I just enjoy the music. Trueplay also makes a huge difference In my experience. The ones sound best below 50% volume in a smaller room because above that the dsp starts struggling. That scenario fits my bedroom well. The fives sound best at or above 50% and I use those in a larger room. Between trueplay and the rudimentary eq I have been more than satisfied.

 

[Darwin]

Are there any differences to the sound signature of the Powernode against the Sonos? I have been considering that too, but the review of the DAC in the Node, which I assume is the same in the Powernode, has put me off along with the significantly higher price.

I’ve tried both and Bluesounds software and support is shit. Sonos is so widely used they have a much bigger user community too.

 

[Darwin]

I've read through this thread a couple of times and think that this might be the best one box solution for me. I'll be using all digital sources (TV via HDMI ARC and streaming FLAC files from my android phone) and currently use a Qualcomm DDFA based amplifier. This amp should provide much more power and convenience and the sound from digital sources should be unaffected by the line issues.

The line “issue” is way overblown. This entire review was disappointing.

 

[Darwin]

Alas, most users of Sonos probably wouldn't have paid up for Roon. As you say, a huge glaring error to not have auto room correction

Disagree. Check the Roon forum. Lots of Sonos users.

 

[MaxBuck]

I’ve tried both and Bluesounds software and support is shit. Sonos is so widely used they have a much bigger user community too.

As a happy Bluesound owner, I have to disagree strongly with your characterization of both software and support.

With that being said, it's hard to criticize user friendliness of the Sonos ecosystem. It's pretty great from all I've seen.

 

[mr.west]

This is a review and detailed measurements of the SONOS Amp wireless/wired networked amplifier. It was kindly purchased by a member and drop shipped to me for testing. It costs USD $599 and seems to be price protected. This is the second generation amplifier from SONOS. The first one lasted until now from company's beginning.

If you are not familiar with SONOS, they pioneered easy, plug-and-play networked/wireless multi-room audio. They aimed high as far as fit and finish, often compared with what Apple would design if they were in this business. Their offerings became so popular that they took the company public. Alas, they have lost direction in the last few years, missing the boat on voice recognition and smart speakers from likes of Amazon and Google.

Back to the product, from industrial design point of view, it is quite a departure from the original SONOS Amp:

View attachment 22961​

Amplifiers don't usually have "pause/play" on them but this one does as it is an end-point in a streaming platform. So music piped to this Amp can be put on pause or played using the center icon. The left set of dots lowers the volume and the right, raises it. What is wrong with the traditional up/down symbols to have needed reinvention is beyond me.

The circle above may make you think it is a subwoofer but it is not. It mates with the bottom of the unit allowing you stack them without much of a seam between them.

The back of the unit exemplifies what happens when the company has too much cash on hand and wastes it on useless things:

View attachment 22962​

I am referring to the power socket on the left. It seems to be a proprietary connection, mating with a beautifully made power cord. It looks very nice when plugged in but why on earth would I care what the back of the unit looks like in this regard? Granted, the cord is flexible and feels nice in hand when you plug it in. I shutter to think how much it cost to tool the socket and power cord including the regulatory and safety costs. If the final outcome is that if I need a longer cord I have to go to SONOS, they deserve a few curse words on that.

Somewhat similarly there are banana sockets but they are flush and custom made in metal. You are then given adapters like the one I have plugged in on the "LEFT" channel if you want to connect bare wire. The metal banana jacks are very tight and provide a nice secure connection. But again, I hate to think how much was spent on mechanical engineering and single sourcing of these jacks.

For the first time (?) there is analog input and SONOS shows this playing from a turntable in their promotional videos. The jack seems to be smart in that if nothing was connected to it, it would refuse to "play" from that source.

There is a sub output which I like but did not test. Likewise there is an HDMI input but since it does not pass through, I could not test with it.

The paint on the SONOS Amp feels very nice but is a huge smudge magnet. It picks up oil from skin from barely touching it and I could not wipe them clean with a microfiber. You will need some kind of solvent to keep it clean.

There are dual Ethernet inputs. Why, I am not sure. There is of course wireless input. Just plugging the unit in allowed the SONOS app on Android to find it but could not talk to it. I had to push the button on top left to enable it to find it. As is typical here, it immediately wanted to update the firmware in it. Overall, I found the messaging in the app cryptic and uninformative.

The rest of the user interface is also rough as far as usability. Why do I need to "browse" to select the line in as an input? Why is the unit called a "speaker" in settings?

There is airplay support which allowed me to stream content to it from my Roon player. It takes priority over line in so if you are playing from that input, it will be overridden and streaming content will play. While there is a volume control in SONOS app, when you stream using airplay, it takes the volume control from source player. This provided quite a surprise when I streamed 0 dBFS reference tone from my player and watched the power meter in my analyzer peg to max! Thankfully I was not using any speakers connected to amp.

Speaking of volume control in the app, at least on Android, it has very coarse steps to control line in volume. I don't know how this is usable in practice. A single step would go from 6 to 12 watts of output or some such thing. The front panel controls seem to do the same thing (?).

In advanced settings, there is a sensitivity selector from 1 to 6 (?) with 2 being the default for AV components. There are others for itunes, etc.

Browsing local content on my phone was fast and trouble-free.

Measurements
I connected the analog output of my Audio Precision analyzer to Line in and used balanced connection to analyzer/dummy load to measure performance at nearly 5 watts with 4 ohm load (280 milliwatts output level from analyzer):


View attachment 22963

This is pretty disappointing. Looking at the FFT spectrum we see that the distortion products are below 100 dB yet our SINAD is only 67. This tells us that the SINAD/THD+N is dominated by noise, not harmonic distortion. We can verify this by separating the two in the Audio Precision analyzer:

View attachment 22964

The figure on the left includes THD+N meaning it has both Total Harmonic Distortion (THD) plus Noise. Using signal processing we can separate the THD out of it and compute that part as shown on right. As we see, the THD component is 1/6th of the total, confirming that noise is our enemy here, not distortion.

Thinking that the line in may be different than digital streamed content, I used Roon player to stream the same 1 kHz tone to Amp and got this (ignore Gain):

View attachment 22965

Wow, quite an improvement! How is this possible? In the streaming scenario, a full amplitude digital file is played and volume is controlled in software. In other words, the front-end of the unit gets full signal. In the case of Line in, I am keeping the volume at max and lowering the input level to get to same power output. So it seems that the front-end noise is an issue for Line In.

Using full amplitude of 2 volts we still get rather disappointing performance:

View attachment 22966

85 dB? This is far worse than CD (96 dB).

Frequency response of Line In gives us clues as to what is going on here:
View attachment 22967

We have a very sharp brickwall filter at around 20 kHz. It is causing peaking/attenuation in the "transition band" depending on which channel you look at. It is clear they are digitizing the input but why use such a low sampling rate? Aren't turntable folks going to get upset that you can't even reproduce 20 kHz cleanly?

On the low end, there is a drop but part of that is because I had to select AC input which puts a 10 Hz high-pass filter. Measurements with DC input on the analyzer completely confused the measurement system (due to input DC offset?).

Power measurement using 4 ohm load produced this:
View attachment 22968

SONOS rates the Amp at 150 watts into 8 ohms. Here we are seeing over 200 watts of power using 4 ohm which is excellent. During the test I could barely detect the Amp getting warmer so efficiency is quite high. Alas, so is the noise level. Again, this is using Line In with its higher noise level. Best case though at maximum power is in entirely different category than our reference quality Hypex NC400.

Wideband FFT spectrum give us insight into operational design of the unit:
View attachment 22969

We see a peak in noise at nearly 98 kHz. This "smells" like a power DAC running at that sample rate. Therein lies the issue with power DAC (or "digital amplifiers") in that their switching frequency is very close to audio band unlike class D amps which switch in hundreds of kilohertz. Peak level is -53 dB which indicates good filtering.

Line input (in red) shows secondary anomaly. It has a peak at 21 kHz. Guessing what is going on, there is noise shaping in the ADC which explains the rise prior to that frequency. And then some kind of sharp filter to cut off everything after that.

Conclusions
It seems to me that SONOS has partially lost its way, overspending on mechanical engineering, and underspending on features people really wanted (e.g. voice control). Usability of the software is worse than I expected just the same.

Line in input is really poorly implemented. I don't know why any self-respecting turntable fan would want to use it. It might come in handy though to route TV sound through it that way.

The highlight of the unit is copious amount of power at 4 ohm in such a small and cool running package. I am not sure there are many options in the market with so much power.

Subjectively, that great amount of power may cover the sins I am seeing elsewhere. Objectively though, I would have wanted to see more engineering go into unit to keep its noise level at bay, than making fancy power cords for it.

Overall, I am going to leave the SONOS Amp without a recommendation one way or the other.

------------
As always, questions, comments, recommendations, etc. are welcome.

Weather is supposed to get warmer so I am thinking of cleaning up the RV to get it ready for trips and need money for Diesel fuel. So I am going to pass the had to collect some money using:
Patreon: https://www.patreon.com/audiosciencereview), or
upgrading your membership here though Paypal (https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054).

Amir, I appreciate what you are measuring and trying to prove with audio science. However, it is not like stuff that measures poorly by these standards cannot sound very good. Amir, you like to state human hearing has a ~115dB range. However, most formats people listen to cannot even come close to this. The typical vinyl recording is 60-70dB of dynamic range. Additionally, in a room, there is usually some ambient noise 20-40dB which would easily conceal a lot of the artifacts you like to point out below -90 anyway. I take your review as a bit of a stacked deck compared to a tiny DAC with no power supply. We know DACs do one thing extremely well.

 

[AlexOak]

Can’t see any power measurements on my Marantz pm7000n but I’m thinking of getting a Sonos amp instead, wanna scale down some things in my living room. Do I give up power by doing this or do I gain some?

 

[staticV3]

Can’t see any power measurements on my Marantz pm7000n but I’m thinking of getting a Sonos amp instead, wanna scale down some things in my living room. Do I give up power by doing this or do I gain some?

Here are some measurements of the Marantz:

Stereo: Produkt

www.stereo.de

MARANTZ PM7000N

PM7000N to nie tylko najnowszy wzmacniacz zintegrowany Marantza, ale w swojej kategorii urządzenie wręcz przełomowe. Od lat najwięksi producenci ...

audio.com.pl

Looks like the Sonos has more power.

 

[Willem]

With the Sonos you get more power. And as for the measurements, I think using the analogue input for measurements produces quite irrelevant data: this amplifier is intended for streaming digital sources. And yes, it would be nice if the line input was also good, but I expect most real users to not actually care very much.

 

[AlexOak]

With the Sonos you get more power. And as for the measurements, I think using the analogue input for measurements produces quite irrelevant data: this amplifier is intended for streaming digital sources. And yes, it would be nice if the line input was also good, but I expect most real users to not actually care very much.

Won’t be using the line in anyways so, but the hdmi should measure the same as the streamer section?

 

[Willem]

Should do.

 

[pjug]

Won’t be using the line in anyways so, but the hdmi should measure the same as the streamer section?

This is a good excuse to measure an amp with the E1DA Cosmos ADC (I recently bought this). Also I am wondering if the Sonos Amp can now measure a little bit better than what Amir measured, since Sonos S2 supports 24 bits which it did not at the time of Amir's review.

Also, with regard to the analog input noise measurement: a lot of this is the ADC noise shaping above 10kHz. The A weighted noise figure is probably much better.

 

[pjug]

I wanted to follow up on my post above. I measured the Sonos Amp with my new E1DA Cosmos ADC. I was curious about the nature of the noise of the Sonos with analog in and also I just wanted to play with my toy. I set the input to 0.29V and adjusted gain for 4.6V output (so about 24dB gain), as close to what Amir used as I could do without too much fiddling. The results were similar to Amir's, and shown below. When I turned off the tone and measured noise I got -71dB, so a little better than Amir measured (69dB SINAD), but nothing to quibble about I would say.

What is interesting is that the A weighted noise is about 6dB better, -77dB. This I assume because a lot of the noise is above 10KHz. Also, at lower gain the noise is much better. At 12dB gain (still with about 5V output) the noise is 12 dB lower, so seems to scale proportionally over that region. You can see this in the plots below.

For me this is just a curiosity. I never use analog inputs with this amp. But if you do want to use them, they probably aren't as bad as Amir's 69dB SINAD number would have you believe on the surface.

 

[Ein]

With the Sonos you get more power. And as for the measurements, I think using the analogue input for measurements produces quite irrelevant data: this amplifier is intended for streaming digital sources. And yes, it would be nice if the line input was also good, but I expect most real users to not actually care very much.

Here we have also data about digital section, and AMP shining there. So, like you said, this animal is for streaming, TVs/AVs opt/ARC purposes. And one more thing - ADC section is not for digital (what digital? CD? Different DACs or streaming is useless here, cos DAC/DSP in AMP is very, very good for that) but for analog, especially gramophone. They have in accessories Pro-Ject for Sonos "needle" and ADC section is more than sufficient (14 bit, RIAA from gramophone or pre-phono) for that task. I have AMP and this is my best audio component (I have also many HiFi/end devices, but...) for sure. When you want stream needle in multiroom environment (salon -> office in my house) here we go.

It have a lot of power (digital amp with tons W without distortion), fantastic integrate with TV and also (AV installation around AMP) projector, different video/entertainment sources ie consoles etc. Amazing thing. Work flawless, controlled 100000 apps -> Roon ecosystem/voice/traditional RC... yes, all here. Like I said: tip top sound device, OMNIPOTENT device.

PS. Sonos multichannel here, you have 4.1, or 4.2 (Sonos Subs)... its also fuc..g good!

 

[TSB]

They should have added voice control years before Amazon did with Echo. Any focus group testing would have shown the difficulty of trying to find and play music with a smartphone.

This is no different on all the mobile phone companies that missed the boat on smartphones and app stores, letting Apple eat their lunch with iPhone. Where is Nokia now?

IMO you're underestimating cost and difficulty of creating usable voice control. They would probably have ended up sinking a lot of money into a second-rate implementation, like most who tried this did (my company has an in-house VA..). There is a reason why only the biggest of the biggest had some success in this area. And their costs are covered by the goal of dominating the whole IOT/embedded space from cars to fridges - not just selling some speakers. To be competitive, Sonos would have to launch head-first into full competition with Google/AMZ on a voice assist, not something that would make any shareholder happy. Business-wise it makes much more sense to me to latch on to an existing implementation, i.e. to support alexa or GVA, instead of risking the huge R&D costs.

 

[Ein]

IMO you're underestimating cost and difficulty of creating usable voice control. They would probably have ended up sinking a lot of money into a second-rate implementation, like most who tried this did (my company has an in-house VA..). There is a reason why only the biggest of the biggest had some success in this area. And their costs are covered by the goal of dominating the whole IOT/embedded space from cars to fridges - not just selling some speakers. To be competitive, Sonos would have to launch head-first into full competition with Google/AMZ on a voice assist, not something that would make any shareholder happy. Business-wise it makes much more sense to me to latch on to an existing implementation, i.e. to support alexa or GVA, instead of risking the huge R&D costs.

Yep, 100%. Now, they have music/content-centric Sonos Voice Control and this is cleaver move, cos not AI (after decade +/- still dumb), but control) just alternative for RC/app.

 

[Xaero]

I feel that this review is very.... weird... I personally never heard about the reviewer and don't know who he/she is or what credentials this person have. But the feeling I get is a mixed bag.

The reviewer seem to have capabilities and somewhat basic understanding how to measure speakers and amplifiers, but yet does not recognize what power cord is used for the device in question.

The power cord, it is not proprietary, it is a stock standard IEC C7 power cable that has been around for decades. Literally anyone who has been into electronics for more than 5 minutes should know this.

The double ethernet jacks is also very simple to understand: One is input, the other one is uplink. I don't understand how this is even a confusion.

The cabinet on the AMP is not "paint", it is molded plastic, it doesn't come off or wear over time, it is black all the way through the material.

The recessed RCA connectors does not cost more to make than having them on the outside. The cabinet is tool molded and would cost the same regardless. The flush banana tube connectors is actually cheaper than having a 5-way binding post on the back, so again on this point the reviewer was wrong. If you want, you can just verify this with Sonos themselfs.

Now, in regards to distortion, I only use Sonos AMP with streamed audio as input (TIDAL), and there is NO distortion or noice that is audible from the output, literally none. Maybe measurable, but not audible.

It's all good to make measurements on products, to scientifically verify things. But keep in mind, if someone that makes measurements doesn't do them 100% correct, the result is meaningless.

All I want to say is, LISTEN to the device and trust what YOU hear and feel. Don't put all your trust in measurements, especially when they are made by someone who doesn't know a IEC C7 cable when he/she see one.

 

[Willem]

I do think measurement is important, but the question is what to measure. Measuring the analogue input on a device that is primarily used for streaming and to connect via hdmi does not seem to make much sense.