I think you are experiencing a grounding problem. I resolved buying a ifi groundhog but more capable people simply build a purposed cable.

My problem with the humming has been resolved. i received the ifi groundhog+ and as suggested by Rob Watts I earthed the amp Humming is gone!

Thank to everyone on the forum for being so helpful. That’s great!!

Hello everyone, I'm sorry for posting another discussion about the power supply to the QUTEST but I'm really struggling here and reading trough the discussion didn't provide a definitive answer. I 'm looking to upgrade my DAC (Audiolab M-DAC) and I bought for an audition a QUTEST and a Matrix...