I am looking for help and opinions from expert users for sound-absorbing panels with our systems

What specific problem are you trying to solve with these panels?

Depending on your specific issue the answer varies greatly.

In the majority of cases the answer is going to be you don't need panels or panels won't solve your problem.

Hi! Thanks for your time and kind reply! I'm actually looking for ways to improve the sound, not because I'm having any particular problems, but rather because I thought leaving a room completely untreated wasn't a good idea. So I was thinking about installing some panels that would do their job, at least in front of me and above the TV. I have some objects scattered around the room, metal paintings, etc. As for the ceiling and sides, I realized they might be more of a problem than a help, since Sonos uses the walls to "reflect" the sound.

If you don't have a problem panels aren't going to solve it. :-)

With no problem to solve how would you decide what type (there are several) of panels to add, the wrong choice could cause you to have a sound problem as well as costing a small fortune, effective panels are not cheap, cheap panels are almost always not effective.

Think of it like a wall, if you just need a wall, you are good and need to do nothing. If you want to see through it you need a window, but if you want to walk through the wall you need a door.

You must identify the problem  before you can identify a solution.

If you just want panels for appearance you can make some and not create a sound problem. Make your own with a simple wood frame and speaker-cloth cover, they will look very nice, impress all that see them and not hurt your sound.

Edit to add: Yes Atmos imaging will likely be more disrupted than stereo imaging. The main issue is going to be disrupting your frequency balance / room response though.

Thank you so much! You're very kind!

Just to answer a quick question: is it as I think? Would the audio Sonos sends to the ceiling (Atmos) and side walls be "damaged" by possible sound-absorbing panels because it doesn't bounce properly toward our ears? This is just a technical question...

If you absorb essential frequencies before they are reflected into the room it is not really different than buying a junk speaker that does not reproduce the absorbed frequency.

As it is unlikely you will add panels that absorb the full frequency range of the individual speakers equally across their range you will hear unabsorbed sound and not the absorbed sound so it will likely sound very odd if the source material contains Impacted frequencies.

I'm not saying accoustical treatments are bad or ineffective, but that they are not like a lightbulb, where you just stick in a bigger one to get more light, they are a tool that must be precisely selected for the task at hand.

 I did a fair bit of adjusting my main listening room's response here, I avoided using panels as I find them less than attractive and I'm not trying to impress folks by following the nonsense audiophiles (more letters than fool but similar meaning in my opinion) often recommend. My issue was a sheetrock open-plan L shaped room, tile floors with a vaulted ceiling. It was far too live and echoed badly. Heavy wool carpets in one leg and center and a thick synthetic one with a foam back in the other helped. Adding a thick thermal curtian along the longest wall also helped.

Once I switched to Sonos I found the Trueplay tool did as well as the Denon tools for fine-tuning the room's response.

Thank you so much! You were very clear. :-)

Do some reading. I was not able to find any articles that I considered “very good”, Here is a very basic starter and there are links to additional starter articles.

Thank you very much!

Not a bad introduction but a bit weak on identifying accoustical problems before applying 'solutions.'

The test equipment discussed sounds excellent, I've used much older, more primitive versions of some of it. Using it with Sonos, aside from a Port feeding a conventional system would be problematic.

Interactions with Trueplay and the changes Trueplay would make to the changing room accoustics would be interesting, sadly there is no way to view them so you'd be reduced to listening tests. Still if you can identify a problem Trueplay can't solve room treatment is an option.

Spousal approval for much of it is iffy in living spaces, but in a dedicated home theater room possibly acceptable, but in that type of space Sonos may not be the ideal solution.

Ran across this book, sounds like a wise investment before spending a lot more on room modifications.

https://www.amazon.com/Master-Handbook-Acoustics-Sixth-Everest/dp/0071841040/ref=dp_ob_title_bk