Mark Levinson No Sound

[JDsGX]

I have an '04 GX with the ML sound system. I'm reasonable happy with the sound except the 6-disc CD player doesn't work. I play CD's through the DVD player.

A couple of months ago, the nav screen went blank and no audio from the radio. I checked the fuses and none were blown. At least not then. After reading tons of listings on another forum, I figured my amplifier was toast. 

Today, I went out to look at some of the other fuses besides radio 1 and 2. They were all fine, but radio 2 was now blown. I replaced that one, which instantly blew, or so I thought. I turned on the ignition and the nav screen came on briefly, then went blank again. I then disconneced the battery and put another fuse in. I heard what I thought was another fuse blowing. However, when I went to the store this evening, the nav screen came on. The backup camera works. I turned on the radio, but still no audio. 

I am assuming my amp is toast. Am I correct? Or is it the radio itself? No, I don't want to swap it out for one of the Android systems out there. It may look nice, but I'm not spending $1k and up on a radio.

Any advise from those who have had a similar problem are appreciated. And I know you are out there as we all know the ML system is not too good this long after it was made.