Sonos Amp and 3rd party subwoofer issue

Show first post

121 replies

Sorry for my stupid question… Do I need a passive or an active sub using an amp with two normal (Bose 251) speakers? 

Sorry for my stupid question… Do I need a passive or an active sub using an amp with two normal (Bose 251) speakers? 

It’s an active sub, or you can use a Sonos sub - just to add the Amp user-guide/manual is available here too, if you need further information:

I've just submitted my ticket to support as well.  Hopefully there's an answer soon.  I'll update here if I get anything tangible.

AWHS has it right about what to do with setting up your 3rd party sub. I have the Martin Logan Dynamo Sub 1600X with the Martin Logan Wireless kit connected to the Sub Out of the Sonos Amp. I also own Sonos Connect Amps (which were easier to set up with a 3rd party Sub). With the Sonos Amp I also drive a pair of Paradigm Studio 60 v3 tower speakers.

So yes, go to the Sonos Settings and add sub, stay away from the Sonos Subwoofer settings. This section should be a little more clear.

You may be best to have your 3rd party sub always on as opposed to standby. With the Sonos settings have the sub level up high and adjust other settings according to your sub manual and cater to your room size and placement. Sub adjustments can be a science. Note : The Martin Logan Dynamo Sub has an app to fine tune it’s settings from your couch via Bluetooth. No need to adjust the manual controls on their latest higher end subs.

As for the Sonos Sub, it is not over priced for what it does. It’s impressive, I use one in another zone with a Sonos Connect Amp. But it’s no match for the Martin Logan Dynamo 1600 :)

Just to provide some hope for people. I have the new Amp connected to an Energy sub and Mirage speakers. I’m not using it for TV. It’s all playing perfectly and the subwoofer is powering just fine.

I will say the line level is low and I had to the sub volume knob to about 75% and it’s all the way up in the Amp settings. 

It sounded good playing lighter rock music like Gin Blossoms and thumped when I put on In Da Club by fifty cent.

I’m about to buy the AMP to connect a 3rd party Subwoofer with a pair of Play:5 - Nothing else will be connected to the AMP.  Would I have the same issue as mentioned in this thread?

Even if this works, it will involve clunky workarounds. Why bother? Why not just get a Sonos Sub?

I have the same issue and reported it to Sonos. My setup includes two Q Acoustics 3020 bookshelf speakers, a Pioneer SW-8MK2, and an HDMI connection to my TV. I got the following troubleshooting steps from a Sonos engineer:

1) Connect your Subwoofer to the Sonos Amp.
2) Disconnect your bookshelf speakers from the Amp (please disconnect the speakers from the Amp side by removing the speaker wire adapter).
3) Now test playback with only the Subwoofer. Does this work properly?
4) Regardless of the result, please submit a diagnostics while it is playing in this mode.
5) Next, re-attach only the speaker adapters to the Amp but without the speaker wires. You should effectively only have the Sub and adapters plugged.
6) Once again, please test playback and provide a second diagnostics.
7) Lastly, re-attach the speaker wires to the adapters and test one more time along with submitting a diagnostics after completing the test

Unfortunately, I received these tips after I returned my subwoofer (Sonos was taking a while to get back to me, and this thread didn't leave me with much hope that this issue would be resolved). The bookshelf speakers are serving me fine for the time being, but here's to hoping that the steps above will help someone else with this issue.
Userlevel 2

Hi everyone, thanks for sharing your experiences with different devices and the Sonos Amp. We’re always interested in seeing what you have to say, and are eager to investigate any issues that might come up. Our engineering team has been looking into this issue and would love some more information. Currently, there isn't a major trend that has been identified, but they'd like to see some more cases where subwoofers and the Amp aren’t behaving as expected. 

If you’re having trouble with the Amp outputting low or no audio to a subwoofer and haven’t worked with our support team yet, please feel free to reach out to us using the contact details here. The support team will help sort out issues where possible, and if needed, they’ll gather the right information and get it up to the engineering teams for investigation.


Ryan - I appreciate your input. Is there a case number or something that we should reference when we call in? I spoke with CS at length at this issue a few days ago and was told that they “have never heard of this issue.” Given that this thread has 10K+ views and hundreds of users with the exact same issue, that was frustrating. Please let us know what we can do to facilitate a resolution to this issue.


I use a Sonos Amp connected via Line-In to my computer. I’m using Definitive Technology bookshelf speakers (ProMonitor 800s) and a matching Definitive Sub. I have been having the same issues - no sub output from the Sonos Amp. I tired several things, including unplugging/plugging in the sub along with trying different outlets in the room. Ultimately, what WORKED is setting the volume level in the Sonos App on the Line-In output (my Amp) above 50. Then I adjusted the volume on my computer to suit. This kicks the sub on … perhaps because there’s more “power” coming from the Amp. I have experienced this before with subs that have power, but an auto switch (no native on/off manual switch). Try it if you’re having issues. It worked for me, and it kind of makes sense. You have to force the sub to kick on, and the best way to do this is from the Amp itself, through the App. PLease let me know if this works for you as well. I would be interested to see if this is a widely acceptable solution. 


Those steps appear to be a test to ensure the subwoofer output is working at all. I think everyone with the issue can confirm the sub out is working, just at a greatly reduced level from what the speakers are outputting (easy fix in firmware for them, just increase the starting sub output level)
I can't believe their engineers can't pull one off the shelf and test this, it would literally take two minutes. Maybe they don't have a 3rd party sub and have only used the Sonos sub, which connects differently and I'm sure works perfectly.

Can anyone suggest an alternative box that provides the same functionality and similar power? Will have to replace the Sonos Amp if they won't address this. I replaced my Pioneer XC-HM86 with the Sonos Amp. The only thing that was lacking was power, otherwise a great device and even has a color display screen.

AudioControl Rialto 600 with a Sonos Port.

I’ll be in the same situation - has anyone used a sub that has just a single input with the AMP - I’ll end up with two subs so I’ll have to split the sub out which sounds like it will be a problem.

I’m a Sonos noob ready to buy a Sonos amp to replace my old home theatre receiver but the wired subwoofer issue here is keeping me from purchasing. I have a good powered subwoofer I like and see no reason to have to buy a new $700 wireless Sonos one. I want to use the amp, 2 bookshelf speakers (with center channel emulation) and my sub which is easily wired to the amp. I’m not using any surround speakers, I have them now and have decide to give them up and the center channel too to keep things simple and clean. I don’t watch a ton of action movies, more likely to listen to music. 

So, does the powered subwoofer output work or not? I’m not buying it unless it does. 

Userlevel 4
Badge +3

Is anyone still experiencing any of these issues after the update? I have a Polk HTS-10 connected to the Amp through the sub out RCA  output. It sounds great when the sub is first powered up; none of the volume issues that were initially reported in this thread. Once the sub goes into standby mode though, the Amp will not wake it up, even if I increase the volume to uncomfortable levels (50% or more). In the settings for the Amp I can see that it still senses a sub is attached. I can only get the sub working again by unplugging it from power and plugging back in. This happens with both the LFE input and R/L low-level inputs on the sub. It does not have high-level inputs and does not have an “always on” option, just auto detect or 12v trigger.


I’ve tested the sub with other components and they all wake it immediately from standby with no issues.

The only way to connect your 3rd part SUB is to configure your Amp in a separate room to your Arc or centre speaker, if you add the AMP to the same room setup as your Arc then the output is disabled.

This is a bad marketing move and just a money grab to get you to not use your existing Sub and to purchase the Sonos SUB…

If you configure your Amp in a sperate room and add your L + R speaker and Sub they work, but when you put them all in the same physical room as your centre speaker the sound is out of phase and it sounds bad

Userlevel 2

I had the same problem when I got my amp and connected my subwoofer with a simple rca cable: the sub output was very low and I had to crank up the sub level in the Sonos app. Everything was fine after I switched to a y-cable (1-male to 2-male), now connecting both (L+R) inputs of my sub. These cables are available for around $10. Maybe worth a try...

 Can anyone confirm this resolves the issue? This would seem to a ridiculous oversight by Sonos if true.  

Naturally, I have the same issue.  Sonos has disabled the sub out if you are using the Amp as a surround configuration.   After talking to someone at Sonos(somewhere in a foreign land) they have informed me that the sub “out” has been disabled since they can't guarantee the quality of the sound when using a third-party subwoofer, however, the same concern does not seem to apply to third party speakers.  I am using the REL sub now on my Amp, and it works perfectly so, I don't believe this is the true reason.  Any sub will work fine, but Sonos wants you to purchase their own sub.



Userlevel 7
Badge +17

System posted twice.

Just to update everyone. I was on the phone with support who took over an hour to understand what I was asking and tbh, at the end of call really didn't address my issue. They wanted me to hook up the sub to my old connect amp and switch back and forth between that and the Sonos Amp while playing the same source to see if there was a volume difference. There is, which I stated within 1 minute of the beginning of the phone call. She put me on hold a few times and basically told me I need to contact the manufacturer of the subwoofer and ask them about level adjustment. It's not their product that is the problem, it's the Sonos Amp. She was also asking me to make level and XO adjustments on the old connect amp. Ummmm, it doesn't have seperate subwoofer adjustments like the Sonos Amp does. Anyone know how to skip the flow chart readers and get to a support agent that is knowledgeable about the product they are supposed to support?

That information you were given is incorrect, as I understand it. The Sonos system is only sending the surround information across the link to the Amp supplying power to those speakers, and has never included the LFE channel in addition. 

The feature has been requested since the initial release of using a CONNECT:AMP to drive surrounds, and has yet to be included. One doesn’t know if there is a technical, financial, or marketing reason as to why it hasn’t been changed. 

Hi Kalorama,

The wonderful Sonos engineers have decided that you do no need the sub out when setting up your AMP as surrounds. In other words, they have purposefully disabled the subwoofer signal instead of giving you the option to turn it on/off as you like.

I can only speculate why they did this,

Oh dear, how misguided is it possible to be?  This has not been ‘deliberately disabled’.  Why on Earth would Sonos do that?  The nature of the connection of surrounds in Sonos is that they take their data in a passive way from the device running the HT setup (Playbar, Playbase, Beam or another Amp), and in this role it has not been possible to control the Sub output  The lines-in on surround speakers are similarly affected and cannot be used.  For similar reasons you cannot play Airplay 2 to surround speakers.

So do you really believe that Sonos have decided deliberately to deny their customers a whole range of features that might be useful to some of them?  

You can use the third party subwoofer where an Amp is used as the main ‘room’, i.e. for the front speakers.