Hello, this unit about 5 months old and used maybe 50 hours because I have other amplifier, amp almost new and looks like new , working flawlessly and sound real good , powerful enough to run any headphones I have original package The Cayin HA-300MK2 is a fabulous sounding 300B SET flagship headphone amplifier. It has that classic slightly sweet or euphonic coloration combined with a seriously impressive holographic staging quality. Neither does it lack power for demanding headphones so dynamic range is never going to be an issue.