I've had three hours, I traveled a little doc, and!! 3 modes NORMAL "HALF NORMAL" and "THROUGH", I read, I look at the diagrams, and I realize that if I am not mistaken, I can connect headphones behind the patchbay, I try, I use a sound card "M AUDIO FAST TRACK ULTRA 8R" having 2 headphone outputs with independent volume control, I switch the channel 23 and 24 of the patch in "HALF NORMAL" I enter the front upper patch (important) 2 headphone output of my FAST TRACK 4 I plug headphones into each rear exits 23 and 24 of the patch, IT WORKS !!!!!! no lowering of standards, without breath, in addition to other functions, a "HALF NORMAL" is hell, it does not constitute a headphone amplifier (which I get next week) because no independent volume for each output, but a patch really versatile, I did not expect so