The HD 550 are Sennheiser's lightweight open-back wired headphones from the HD 500 series, with angled 150-ohm transducers and a low clamping force, suited to long music and gaming sessions.
Reviewers agree the sound is neutral, balanced and natural, and that the light build stays comfortable over long sessions; Headfonics found fuller bass than earlier HD 500-series models. SoundGuys found the tuning less exciting than some may want, What Hi-Fi? noted the sound leakage and close competition from other Sennheisers, and Headfonics found the stock cable poor.
Dynamic, open; custom 38 mm 150-ohm transducers made in Tullamore, Ireland, angled towards the ears; 6 Hz – 39.5 kHz; 106.7 dB SPL (1 Vrms); THD < 0.2% (1 kHz, 90 dB SPL)
Battery
Listening time (maker's claim)
No battery (wired)
Design
Weight
237 g
Headphone cable
Yes
Fit and ear tips
Over-ear, open-back; synthetic velour ear pads; synthetic leather headband with soft foam; lower clamping force than other HD 500-series models; metal mesh ear cup covers
Works with
Detachable 1.8 m cable with 3.5 mm plug; 3.5 to 6.35 mm screw-on adapter; balanced and microphone cables sold separately
In the box
HD 550 open-back headphones, 1.8 m cable with 3.5 mm plug, 3.5 to 6.35 mm screw-on jack adapter, drawstring bag
Pros and cons
Pros
+Light at 237 g with a relaxed clamping force
+6 Hz to 39.5 kHz; 106.7 dB SPL (1 Vrms) sensitivity
+Modular design with replaceable cable and ear pads
Cons
−Rated THD under 0.2%, against 0.1% or less for the HD 600 series
−Only a 3.5 mm cable in the box; balanced cables are sold separately
