yes you want to adjust tune the amp according to the way you will wire it all up. when the amp sees a 1 ohm load, it'll put out the power you adjusted it to. now say you adjusted it to that voltage, and wired it to a 2 ohm load (i'm not sure which chart you went by, but ima go by the one in my sig) you'll be getting 600 watts. notice the voltage rating is the same -- 34.64 volts for 600 watts @ 2 ohms and 34.64 volts for 1200 watts @ 1 ohm.
so basically when tuning your amp, you want to adjust the voltage according to the power you want/need with the given ohm load into consideration. which is why the chart includes all those ohm ratings. so that way if you need 500 watts with a 4 ohm load, you wont tune it to a 1 ohm load, which would put out less power since the amp 'thinks' it's seeing less resistance since that's what it was tuned to.
that make sense or did i just ramble? lol i'll try to clear some up if so