I am pretty sure he is talking about setting the gain...
Take the total power you will be putting out (RMS rating, not MAX) and multiply it by the load the amp will 'see', (what your speakers will be wired to, represented in ohms.) Then take the square root of that number..
Get a DMM (digial multi meter, can be had for $20 at any hardware store) and put the probes in the amp's terminals. Turn on a 40-60Hz test tone at the highest volume you will play the stereo (NOT the highest volume capable of the unit), and adjust the gain until you get the number that you figured out earlier.
It's easy. If you don't get it, it's not the ADD, it's stupidity.