Right. I get this all the time in the car. When I have the player running and start the car it goes into low voltage. when it comes out the top end is severely reduced. This also happens (for me) when it comes out of stand-by. It does not happen in AC power, but that's a longer story how I know this.

My setup in car is 5 channel EQ and 10 channel on AC.
hope this helps

I originally posted this bug in v2b3 and has bug#1182. I haven't seen it fixed in v2b7.