I am using 4 different microphones on a 4x12 cabinet. I have them running into a Yamaha mixer and I can plug the headphones into that and the sound is great. I have a left and right output running to inputs 1 and 2 on the 1810C. When I plug the headphones into the 1810C the sound is different. Then when I record it the sound is not the same as the sound on the mixer. Is there some setting I need to change? I am using a Macbook to record. There are no problems with the performance of the Macbook.