Real owners rate these about evenly: 71% of 234 Beyerdynamic DT 900 Pro X owners recommend it, vs 75% of 316 for the Sennheiser HD 650.
Verdicts aggregated from Reddit, enthusiast forums, and YouTube owner comments — affiliate reviews excluded. Sample sizes differ; judge accordingly. How we score
“I bought the 900 proX as my first high end headphone for mostly gaming and music. They caused me to spend another 2k on speakers and a schiit stack because id never heard such beatiful sounds. Worth it”— @Lperry on YouTube
“900 sounds more natural, intimate and less fatiguing but it doesn't stage the same way.”— Bret Halford on Head-Fi
“That joint is a huge weak point in my opinion.”— @drewmorg. on YouTube
“What an incredible difference they make to everything I had before! You can listen to a track and hear subtle details that you did not even know they existed. Wow!”— @marco83 on YouTube
“HD650 with a bum driver, but I was able to solider the voice coil back on, so they work normally again. I had a pair 15 years ago and always regreted selling them.”— kindofbluetrains on Reddit
“I find the HiFiMan Sundara & the Fiio FT1 Pro both more useful for mixing - the Sennheisers have a much more condensed/flat sound with less bass extension than either of those”— @reallyoldcob on YouTube