A former boss was an audiophile with varied amps and headsets. I tested, then backed up my pick with reviews from this very forum over a decade ago. My 650 is still my daily driver and it doesn't mind cheaper amps from FiiO. I have been using an E12K MB and sometimes an E10K for specific applications. I found I don't require a fantastic amp as I can combine with PulseEffect profiles and convolutions.

I'm nothing but delighted with the range of this headset. Balanced bass, crisp vocals, clear instrumentals, and it doesn't skip a beat on busy pieces. I also use vocal free electronic music and epics when working to avoid distraction. It amazes. Also after 11 years the build quality has surpassed expectation.

However..

I noticed the HD650 consistently on sale and recommended it to a friend. I was devastated when he complained. His headset is only marginally better than my Platronics Gamecom 780 with PEQ/Atmos. I'm unsure if it is a bad sample or an explanation of the consistent "sale" going on for this headset. I've asked him to return and review this forum instead...