It could be related to the harsh treble users have been reporting. See this thread: https://en.community.sonos.com/home-theater-228993/sonos-arc-metallic-sound-6843110

You could always try redoing TruePlay with a different iOS device to see if it makes a difference.

Thank you for your reply. I used my iPad for tuning. I might just keep retuning to see if it improves.

lt’s not terribly bad,but needs improvement.I hope Sonos comes up with an answer.

Same problem here, harsh birght sounds on dialogue. even with trueplay disabled.

Sonos are aware of the problem.l just hope they have a fix soon for it.

Did you have contact with them? Do they admit there is something wrong? 

I rang tech support and they suggested a few adjustments which made little improvement.They are aware of problem through this forum.

Fill in form . Make them aware of problem. I guess the more complaints they get the better.

I did fill in the form

What where those adjustments?

Toggle around with voice control and the Night on and off. Neither made any real difference.l have treble right down now and the loud switch off. A small difference,but still too bright .

Set the treble to -8 or -9 but keep loudness on and trueplay on… at least the sound becomes bearable for a 2 hr movie lol

@King Colin : could you describe you're room? large open space, hard flooring, carpet curtains?

My tv room is quite small.Hard floor,curtains not much open space. I don’t think it has to do with acoustics.l spoke again today with a Sonos technician.But we couldn’t improve anything.He did say there should be an update quite shortly.ln this day and age this problem should easily be resolved.

Me too having the issue.

I find it very noticeable when you try to compare with other Sonos products alone (e.g. Beam, One that I have). I have tested for different sources that contain various human voice. The vocal sound from the Arc just sound and feel differently and unpleasantly, with True Play on and off.

Turning down trebles helps to reduce the issue... Hope this issue can be addressed soon.