And lastly, this attachment is a test of my measurement system. This is with the PC sound card's output externally looped to the line input of the same card. Basically, I just disconnected the RCA patchcords from the EMPEG, and put RCA barrels in it's place (so that the input and output patchcords are still in the test path).

This also shows that the slight level offset between the left and right channels in the previous graphs is partially due to my sound card.