Which would hit harder and be a better sub system: 2 10" infinity perfect's running at 800 watt rms, or one IDMAX 10" running at 1000 watts rms?

 

from my experience the two 10s would hit harder. roughly twice the cone area, so more air can be moved. the ID may have more excursion and be an SPL sub, but I would say the 2 would be better for you and your needs.
i had 3 JL 12s and then 1 Digital Designs 9515 back in the day, running off the same power, and the JLs were louder, hands down.

 

more cone area wins..

the idmax will sound better imo

 

If the manufacture gives honest sensitivities you can work out the loudness.

The difference between an 800 watt amplifier and a 1000 watt amplifier (all other things being equal) is just barely audible. What you really want to do is double the power from 800 watts to 1600 to give a nice difference between the two ... 3 dB is a difference that most people will notice but it's not like it's night and day.

 

is that all that 200 watts would add, is 3db?