It will power up but after a few min it will shut off. If I disconnect the interconnects it will stay powered up indefinitely so I'm guessing it is going into some sort of protection mode. I'm running the line level signal from my stock HU (Symphony II) using the Blau adapter re-pinned into the stock plug. I think I've heard that output of the line levels is on the order of 1.5-2 volts. I turned the gains down to 1/4 and it seemed to stay on longer but eventually still shut off before long. Any idea what the problem could be or how to trouble shoot it more? The amp worked fine in my last install off a Kenwood HU so my guess is that it has something to do with the stock HU output...maybe the common ground is a problem for my amp (PPI PC4100)?

I just thought of the fact that the stock HU uses a common ground for the line-level outputs...think this could be the issue? Otherwise I think it has to be something with the output voltage/distortion from the HU tripping some sort of protection circuit in the amp. I have an email in to PPI tech support looking for specific amplifier issues.

Is the amp's chassis isolated from the car's metal structure?

I only replaced 2 pins for the front outputs and left the rears alone so I could keep the Bose amp and speakers for rear fill. The PPI service rep I've been emailing with said it very well could be the common ground that is the problem. I'm going to plug in a portable MP3 player in place of the HU and see if the amp still shuts down. Assuming this is the problem, can I avoid using the common ground from the HU?

<center><img src="http://www.exelaris.com/ttaudio/concert_label_close.jpg"></center><p>You have to ground them! It's the "Com." pin in the line out plug area.

I spliced the 2 ground wires from the 2 channels of the blau adapter into the common ground from the factory deck. So what I have now is the two rear channels of the factory Bose amp and the two front channels through the blau adapter all use the common ground. The Bose amp doesn't seem to have an issue with this as it still runs the rear speakers fine. I disconnected the interconnects from my amp and ran a portable MP3 player directly to the amp and the system played fine for 30+ min while I did some tuning. So apparently my PPI amp doesn't like the common ground. Is there some other way to ground the RCAs other than using the common ground from the factory deck?

I have a post on Sounddomain looking for other grounding options. I don't know if I can just ground the RCAs directly to the car chassis or not. I'd be really bummed if I can't use the stock HU because of a small detail like this.