sony cdx gt10m speaker ground

Long-time auto tech, newbie to this forum. 

Bought this radio for my boat and learned from the installation guide that it has separate grounds for all four speakers (LF, RF, LR, RR).  Instructions also say that I risk a "malfunction" if I use the existing speaker harness that has a common ground for all four speakers. 

I've Googled this topic and find no information - I can see that I might lose the Fader and/or Balance functions but can't tell if this is a real issue or a manufacturer's preference.  Rewiring through the blind areas of this boat will be a serious challenge.  Can anyone help me understand what I would be risking if I used the existing harness? .

Thanks in advance, JJ

Do not try this.  There is 6 volts of DC voltage on every speaker wire of your radio.  If running new wires is not an option, you will need to buy a very cheap (I mean really cheap)  radio that does not have a high power output chip. 

On a high power radio, there is signal on every wire if you ground any wire or one wire touches another, there is a good chance you will take out the output chip.