Combining Amp Power

Some companies let you hook up multiple identical amps and end up with a single output that has the combined power of all of the amps.  But they always require you to have identical amps (same brand and model), plus the special cable to connect them together.

Was it wired up in such a way that each sub was getting the same amount of power?  Cuz obviously it would be easy to just push one sub with one amp and the other sub with another amp and technically that would work but you'd have to mess with the gains to get them to play at the same volume.

can you take two matching amps that say prodce 250 rms watts..to make 500 rms watts and put is on a DVC sub..one amp on each voice coil? 

In theory yes you can do that, but I would not recommend it because the gains have to be set to the EXACT same level and with dial-style gain knobs this is practically impossible, unless you have something like an oscilliscope to aid you.  Also the input signals for both amps need to be the exact same.

Finally, since identical amps do not always put out the exact same amount of power, just setting both gain controls to 12 oclock would not necessarily mean that they're going to output the same amount of power.

Here's a page from JL that deals with this type of wiring.