yeah im getting another one this friday
So wlike you have only one sub right now and plann on adding a second sub later or you have two right now and plan on getting a third later?
I hate to be the one to say it but if you only have one sub right now then don't hook it up...you'll fry it becuase 800w RMS is twice what that sub will handle.
If you have two already then go ahead an wire them up but you better get an amplifier that will do a little more then all three subs rated power at 2 ohms seeing as the subs are 4 ohm DVC three of them would present the amp with a 2.67 ohm load.
If you were to hook all three up to the amp you have now you would be giving each sub 400w RMS but only if at 2 ohms but three 4 ohm DVC subs will get you a 2.67 ohm load so in reallity they would get a little less to alot less then rated power not to mention that we don't even know if the amp you have actually does the rated power the manufacturer says it does.
How many fuses are in the amplifer and what amperage are they?
Example:
My PA A2400DB has four 40amp fuses which = 160amps max current draw.
If the amp does rated power at tw ohms then you should be fine,just set the gains a tad lower.
But please do get back to me on the amount and amperage of fuses the amp has.