What specific model TV do you have? What do you normally watch? When you are experiencing low dialog, what audio format is displayed on the Now Playing screen in the Sonos app?

I use lg c1 , it's like that no matter if it's Atmos or Dolby 5.1 , it's even like that with music. Also with Atmos when playing music beam sound very boomy and the SFX are loud as they should but dialogue with speech enhance on or off don't change a lot. Just make the sound even more flatter but no volume change . I had never problem like this for last 12 months using the setup.

Make sure the TV is set to these settings:

HDMI Input Audio Format: Bitstream

Digital Sound Output: Pass Through

eARC Support: On

Have you adjusted the EQ and tried setting Loudness to OFF? If you are seated close to the surrounds, try setting the Surround Audio levels to a negative setting.

Also make sure the microphone on your phone has been cleaned and the phone case has been removed before you perform Trueplay. If possible, try performing Trueplay with a different model iOS device.

*****I have this exact issue on two separate tv’s and two Beam 2’s. Why can’t sonos provide some answers? This issue is referenced in many forums online. I am within the 30 day return window and I am considering returning them as they sound horrible!!!

What did Sonos Support say, when you called in with your system diagnostic ?

I’m probably just going to return them. It’s happening on two different beam 2’s and and two different TV’s. It’s especially bad on Netflix using apple tv. From reading other threads, sonos issued a firmware update that created these issues and never cared to address it even though it’s all over the forums. Clear to see they aren’t really concerned with their customers. 

Probably best for you, then. Good luck!