I'm putting together my order for the x5M and can't seem to find any information on the "Enhanced Premium Sound #752" Option that comes within the ZPS Premium Sound Package. My understanding is the x5M comes standard with the "677 - Premium hi-fi system". I believe this to be the same as the 16 speaker 600 Watt system that comes with the standard x5's within the "Premium Sound Package"option. So what exactly is #752 available with the x5M? Is it worth it compared to the 677? Any insight would be helpful.