Real owners rate these about evenly: 58% of 93 Sennheiser HD 620S owners recommend it, vs 61% of 231 for the Sennheiser HD 660S2.
Verdicts aggregated from Reddit, enthusiast forums, and YouTube owner comments — affiliate reviews excluded. Sample sizes differ; judge accordingly. How we score
“Just got my 620s yesterday, I like it, which is saying a lot for a closed back. I think it’s easily one of the best closed back headphones not only in the price range, just in general.”— MoonWun_ on Reddit
“Crazy enough, the HD800s and the HD620s share the top spot in my endgame headphones. And the price difference is over €1,000. I just can’t believe what the HD620s deliver for €279.”— No-Desk-1808 on Reddit
“I think technically the 620s but the design of the ear cups means they have this bit that protrudes into the ear cups (I think the anchor for the headband) and it’s quite uncomfortable (at least for me).”— gussic on Reddit
Real owners rate these about evenly: 58% of 93 Sennheiser HD 620S owners recommend it, vs 61% of 231 for the Sennheiser HD 660S2.
Owners point the Sennheiser HD 620S at gamers wanting a closed-back with wide soundstage for competitive FPS, and office/WFH users needing strong passive isolation from surrounding noise.
Owners point the Sennheiser HD 660S2 at hD6x0 owners wanting more bass extension and treble sparkle, and all-day listeners who want a warm, fatigue-free sound.
The most-cited downside of the Sennheiser HD 620S is treble can be harsh, bright, or metallic-sounding, especially in the upper registers and vocals. For the Sennheiser HD 660S2, it's dark, veiled or muffled-sounding presentation.