Help wiring Icepower amplifiers please

I used my multimeter to determine the ASP1000s' big aluminium heat shield base, is also the ground, AND the XLR ground pin, and AC earth pin are already grounded to this. So the amp should play with only the wires hooked up, and without a case.
     So why exactly would I care to make a star ground to the aluminum base plate of an aluminum enclosure, IF the amp is already grounded? 
Seems to me adding a star ground would be asking for ground loops, since the amp is already grounded.
      I am NOT using the DC bus out wiring to another amp module. As far as I can tell, the only connections I have to make is to hardwire the XLR connection cable to my own. Put an AC plug on the power cable. Hard wire my speaker cables to the plastic connector. And it should be fine. 
Please help me understand why I may want to add a ground to the chassis, when my grounded heat sink is screwed tightly to the aluminum chassis ? Thank you for helping me be safe.
I'm not sure exactly what you are asking.

Should the chassis be connected to the ground on the AC cable?  Absolutely yes.

Could the XLR ground be lifted? Often.
The chassis is connected to AC earth ground via the screws into the amps grounded heat shield base. THAT is why I don't understand why I would need any extra grounds.
I believe I understand the manual now. It offers two different grounding schemes. I do not understand why they would offer the second one, with the backplate already grounded. I guess that is why I am not an Electronics guy. I think I messed up asking on another forum. Everyone jumped on screaming about grounding and I was going to die from electrical problems. Then I see an online video of a guy putting the same amplifier board through bench testing, with only the necessary  supplied wires hooked up . So I'll figure I will be okay.
The AC ground is there fore safety.  It should connect directly to the chassis. The reason for this is that the entire point is to short any voltage at the chasis to ground. 

Relying on the amp module to do this is not enough.