Davatwal

Can anyone help me i have a 2001 LS430 and have just been told that the Mark Levinson 86280-0W041 AMP is blown, as everytime i switch the car on there isa pop noise and no sound comes out of the speakers !! The radio is working fine also the sat nav works and the voice works fine too ?? does anyone know ehre i can find a replacement or can get the one i have repaired ?? Kr Dil