Open-back audiophile headphones sold since 2003 with virtually unchanged drivers. Fully user-repairable with available spare parts. No firmware, no Bluetooth, no subscriptions.
Drivers modified with white driver housing (instead of original colors); minor driver revisions made over the years per user reports
Packaging changed; case downsized
Brighter sound signature compared to original 2003 model
Original HD 650 with darker sound signature
Methodology v1.0
1 change(s): 1 moderate | Durability: HD 650 is a long-standing design (20+ years in market) with reports of headband loosening and pad degradation over extended use, but overall robust construction. Material Quality: Classic design with quality components; some concern about cable robustness in older models but improved in later versions. Brand Reputation: Sennheiser has made undisclosed design changes over years (disputed by company but confirmed by measurements), which moderately impacts consumer trust, though the brand maintains strong reputation for audio quality and longevity.