Hello Ruben, and welcome to the forum. Congrats on your new purchase. That is a very nice AVR. I recommend you read the manual, re-read it, then read it some more! Maybe in six months you will begin to grasp all the functions, selections, inputs and processing modes available to you and what the hell they are doing! These processors are complicated these days. The short answer to your question is that you are hearing something different because all those processing modes are taking a two channel signal and processing it in a slightly different manner, (which may or may not be desirable) and which will result in a slightly different volume level for each. For a more in depth insight your going to have to do some research or you may want to visit some of the other forums dedicated to Home Theatre. Folks round here still like to talk bout turntables and vinyl. You will also notice there is no post category for all things Multi-Channel or Music In The Round, which I believe is by design.

RG