Yeah, that's also described in the FAQ in the
installation section. It gives slightly more detailed steps.
It sounds more complicated than it really is. All you're doing is turning the amplifier gains down to the point where you're decreasing the noise floor as much as possible, yet still getting enough gain out of the player's outputs to satisfy your ears.
Another way to look at it is that you're maximizing the useful range of the player's volume knob. If you don't do these steps, then you will either have too much gain (noise during quiet music yet can't turn the volume up very high because it's too loud when you do that), or too little gain (can't turn it up loud enough).