My 300H was delivered in January and shortly after my dealer acknowledged the issue with the ML system
A few weeks later they said California had acknowledged an issue existed. Then a couple of weeks ago they said new amplifiers were being shipped. Yesterday they said it had arrived and today we put it in and it seems the problem is now corrected.
I gave it a one hour test running the volume at 38 on Satellite heavy base music with no thump, thunder or sonic booms experienced. Normally I don't listen to it at a 38 volume. For me I hear most of the instruments well at 34 or 35 and I am a little hard-of-hearing with no hearing aids..
My dealer never had felt it was a subwoofer issue.
So there is hope out there for all of you still fighting the battle with your dealers. Hang in