Richard, This,to me looks like a design issue. Don't understand Lexus's logic behind this. I found the same issue on 2 other ES350 .
I just lodged a complain to lexus at https://support.lexus.com/s/questions-comments
You should also do the same.
The speakers mounted on all the doors sounds VERY low compared to the sound from the dash board speakers.
Also the rear speaker has no sound at all.
Anyone had similar issues?