I really don't understand something... as it turned out in the past few days, because I misinterpreted the manual, the output of the dac line was all turned on, in the above position, because I thought it was turned off, but a few days ago it turned out that it was turned on... actually, now my problem is the fact that I turned them all off, so the preamp is turned off at the moment, and my active speakers, which are on the xl output, started humming... and it never hummed before, it didn't make any noise... how is this possible? and if we set all the switches in the program to the above position, i.e. on, what actually happens??? because the MANUAL does not write anything about this. there can be no ground loop because it was not connected to any of the power distributors, nor was it connected to any of the power cables.. I am sure that this phenomenon depends on the setting of the preamp... I just can't understand that since they are all switched off now, it is in off mode and right now my system is behaving badly... here is a picture of the current setup.