reginaldStjohn
It could definitely be a sort of ground loop between the computer and the Xtouch through the usb cable. This actually might be caused by your transformer if it isolates the grounds between the 110 and 220 sides. When you plug the USB cable in it now creates a path to the UPS ground through the USB cable.
In my studio when I have my Pod HD 500 connected to my computer with the USB cable my amps have increased hum. All my devices are plugged into a surge protection device and to the same circuit.
PC's are noisy and can draw lots of power and create noise and grounding issues in my experience. If it is the USB cable to the computer that is causing the issue you could try to find a USB isolator or have the electrician see if there is a ground connection between the 110 and 220 sides.
Just my thoughts. Good luck.
Useful tips John ! Thanks...will try all of these. I am very skeptical about the transformer coz the issue got better though it did not go away when I connect the xtouch to a laptop running on batteries. In this case, im guessing the ground loop with the PC might not exist but I did have to use the transformer.
Different sockets in the house showed different behaviour. So getting the grounding checked tomorrow.
Will try to find alternative transformer or will get this one checked. I don't know if i can use 220v directly on the xtouch coz the socket on the xtouch reads 100-240v. I am doubtful so to be on the safe side im using the step down transformer.
I read on the net that the carpet in the room can reduce the sensitivity due to isolation of the user from the ground. Will try alternatives for this as well.