I have an ES300 with the Mark Levinson sound system without the navigation system. Since I purchased the car in March 2002, I have had three radios, three driver side speakers, and two amplifiers and the dealership cannot find anything wrong.
The dealership had my car for one week and could not find the problem. I picked up my car and within 30 minutes the volume dropped again. Over the last three days I have lost volume (sounds more like monoral rather than full stereo when the volume drops) at least half a dozen times. I have written Mark Levinson and contacted the Lexus dealership again.
Now they want my car back to do more testing. I'm looking into the Lemon Law to see what I can do at this point.
Anyone else out there experiencing the same problems?