I haven't replaced the switch yet. I've been too busy installing an in-dash cassette, CD changer, new speaker system, and cell phone unit. The stereo sounds superb--top up, or top down.
The Sony ES equipment works and sounds great, but I know the most credit has to go to the speaker system that was engineered specifically for W107s. You can't tell anything was done to the car to install it--looks completely stock (except for the Sony unit, of course).