Just bought me an XC90 (just approved) and unfortunately only ordered the normal sound system + sub. Since this is bad or the speakers hit in the front doors, I thought about the existing, factory-installed power stage to connect another proper 4channel power stage. The cables, which go from the installed power stage towards the speaker, go now first into the new power stage via Hi-Level Input. I use this input, because Chinch unfortunately is not available. I am satisfied with the sound as well. However, only sound comes from the speakers, if I pull off one of the speaker cables for a short time and plug them back in again. As soon as the ignition is off and the power stage restarts, nothing comes out of the speakers. A speaker cable pulls off again and plugs in, then sound comes again. Does anyone have any idea what to do to fix the problem?