After upgrading the S9 to Pie I didn't see much difference in the sound. I'd probably check to see whether Dolby Atmos is enabled because this can make such a difference with the sound quality. You can find this in Settings > Sound and Vibration > Advanced Sound Settings > Sound Quality and Effects > Dolby Atmos.
Thanks for your reply.
That was one of the first things I checked and I just re-checked now and it's active/on.
So this is not the problem :(
I noticed it also. Didn't matter what settings I tried. Flashed back to oreo for now and the audio quality is much better than pie.
So it's not only me imagining stuff..
Does anyone from Samsung actually reads this posts? How do we get this to their attention?