Lets say "Amp X" is a 1000W amplifier.
1000W Peak or RMS makes a difference. RMS is the number to look at. Lets say its 1000W RMS just to make this easier. That now means 1000W RMS at 1 Ohm. When the impedance(resistance in the circuit) of the subwoofers is 1 Ohm, the amplifier will make 1000W of power. Now lets say you are running them at a 2Ohm resistance, the amplifier will only be making 750Ws. So now that 1000W amplifier will really only be sending 325Ws to each sub, not 500. At 4 Ohms you are really losing power. You might get 500Ws out of the 1000W amplifier, or 250Ws to each subwoofer.
Thats as simple as I can make it for that part. As for the gain, turn the gain **** on the amp all the way down(if you have a remote gain **** for your dash, turn it all the way up as well as turning the one on the amp down.) Now pick the hardest hitting sound you have, and turn the volume to the max you will listen to. Most people say around 75-80% of max volume, otherwise it might start getting a little fuzzy which is normal at 100%. Anywho, turn the volume **** up as high as you plan on going, play that hard hitting song, and start turning the gain **** on the amplifier up until the sub starts to clip. Turn it down just slightly from where it starts to clip, and don't ever touch that **** again. Now you will use the remote gain **** that you can install in the dash to adjust the bass later on. That is how you adjust the gain.
As far as bass boost and other such features, make sure they are off and do not turn them on. They are meant for songs like Beethoven and such which don't have a lot of natural bass. Nowadays, all songs have bass in them, so bass boost shouldn't be used.
I have an amplifier thats rated at 9100Ws and we hooked it up to a friends subs just to test it one time, he has around a 500W set up. We kept it down low so it didn't destroy anything, but you can use the most powerful amp in the world on the weakest subwoofer as long as the gain is set properly.
If you have any other questions, just PM me and I will help out if I can.
EDIT- 2 300W subwoofers running at 4 Ohms on a 600W amp would probably only be getting 100-150Ws each depending on the amplifier.
Last edited by Ford12508; 12-12-2010 at 12:43 AM.