Can you confirm that the headphone outputs do not work when you have speaker's selected say to either A/B/A+B and it only works when the speaker selector is set to zero ? Going by the schematics of the X11, it looks like the headphone relay is activated always irrespective of speaker selector position, but then i can be wrong. This is what i can make out from the schematics: The red line denotes a positive 23volts supply with the path considered when speaker selector is set to A, whereas the black is a reference to ground, it still energizes the relay for headphones out no matter what speaker selector is set. Basically the ground of all three relays ( one for speaker A, one for speaker B and the headphone relay are tied together). The positive supply going into the selector board, is always sent to the headphone relay irrespective of what position the speaker selector is set to, so the relay is energized as long as the amp is running ? The only sole purpose of a relay in chain like this, can be to cut off the headphone output in case a dc voltage is present in the output, otherwise the connection is maintained always, just passes through the headphone output, as long as the amp is running. Probably if a DC supply is present, we will not have 23volts activating the reed relay,cutting off supply to headphone jack, in other cases it remains on as long as the amp is powered on. Can you please confirm my understanding ? Or is is possible to verify this in case you have your X1, on the bench, i will ask some of my friends to check if the headphone out works when the speaker selector knobs are changed, in their X11, but i dont know how long it is going to take.