Other factors for determining the necessary gain are the input sensitivity of your amplifier and the efficiency of your speakers. These parameters can and do vary widely from system to system and definitely affect the amount of overall gain required to achieve acceptable listening levels... Your own preference for playback at a particular dB level must also be taken into account, as well as the size and reflective/absorptive properties of your room and listening distance from the speakers. As you can see, there many variables that go into the equation.
