polk PA D5000.5

[Revisualized]

Hello - I just purchased a Polk PA D5000.5 and Polk dxi6500 and Polk dxi525 for my car. My question is I want to add a sub as this is a 5 channel amp... So would I need a 4 ohm sub bc the speakers are 4 ohm or can I go 2 ohm on sub channel?? If I can have 4 ohm speakers thats 70x4 and a 2 ohm amp it's 400x1 I beleive which is plenty of power...if im limited to a 4 ohm sub it is only 200x1 which will still work I guess?

Also would it be better or possible to bridge the front and rear channels of amp for the Polk dxi6500 and put the sub on the sub channel still? How many watts would be going to sub? And power rears via HU?

Thanks for advice

[Vital]

5th channel (as well as front/rear) does not care what ohms you give to the rest of channels.
In other words you can have 4 ohm speakers and 2 ohm sub on your D5000.5 as well as any other amp that is rated for certain ohms.