I haven't done anything on too large of a scale.
The system I installed in my car is;
Kenwood MP3 deck "non excelon"
Kenwood Excelon amp, 300watt
MB Quartz 6x9s
Infinity 6s for the doors
And one Orion 12" sub in the trunk.
I just want rich sound, I don't car if anyone else can hear it.