Just purchased a Yamaha 5016CF board with speakers and monitors. I have read the manual but cannot get good sound out of the monitors through the AUX channels like the manual says unless I turn the gain control all the way up. When doing so it throws everything else way out of control. I shouldn't have to have another amp for the monitors should I? The board is 500 Watts X 4 so it should run the two mains and the two monitors. Any help would be much appreciated. Thanks in advance Randy