If you have two different kinds of power amplifiers and want to use them both at the same time, but they supply different amounts of gain, what do you do? One solution is to add a little bit of attenuation to the input(s) of the amplifier which has more gain than the other one. This is accomplished by inserting a simple two-resistor voltage divider between the amplifier's input RCA jacks and the amplifier's input circuitry as follows: You should first find out what the amplifier's input impedance is. After that, you may have to do a little bit of experimenting to determine exactly how much attenuation to give the amplifier. Usually, about 2dB to 5dB of attenuation is enough. The following tables show the amount of additional attenuation provided by different  R1 / R2 resistor combinations - for use with amplifiers which have specific input impedances.