Sennheiser's new open-back, audiophile-quality over-ear headphones deliver an awesomely open sound stage and are decided not neutral tuning.
Sennheiser HD 660S2 Dynamic Headphones - Magnificent Musicality — Audiophile Heaven
Sennheiser HD 660S2 Review: A New Reference For Headphone Fans - HIFI Trends
Sennheiser HD 660S2 - Reviews Headphone Reviews and Discussion
Sennheiser HD 660S2 review: I'm an open-back believer
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Sennheiser HD 660S2 Dynamic Headphones - Magnificent Musicality — Audiophile Heaven
Sennheiser HD 660S2 Review
Sennheiser HD 660S2 Review
Sennheiser HD 660S2 review: I'm an open-back believer