I was listening to the unit one night when all of a sudden the sound cut out. The front panel LEDs still work. After opening the unit I found all four line in fuses blown. (2) 4 amp and (5) amp fuses. Bought new fuses and installed thinking a surge in the incoming house power could have been the cause. As soon as I turned the unit on the new fuses instantly blew. Can anyone give me an idea as to what could be happening. Thanks.