HD 300 PRO (not HD 300 PROtect) · wired · Sennheiser part 508288
The HD 300 PRO (article 508288) is Sennheiser's closed-back, around-ear wired monitoring headphone for studio, stage and broadcast work. Sennheiser rates up to 32 dB of passive ambient-noise attenuation, a 64 Ω impedance and a 123 dB maximum SPL, and says the viscoelastic ear pads, headband padding and cable are all user-serviceable. It weighs approx. 297 g without the cable. Sennheiser lists a two-year warranty.
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Specifications checked 27 Sept 2026Manufacturer specifications, not a hands-on test.
The nearest checked headphones by key specifications, with what differs from the Sennheiser HD 300 PRO. The first matches the Compare button above.
Sennheiser HD 300 PROtect506898 · HD 300 PROtect (with ActiveGard) · wired
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HyperX Cloud III727A8AA · Black · wiredSennheiser rates up to 32 dB of passive ambient-noise attenuation from the closed back and viscoelastic ear pads, for loud environments such as stages and broadcast.
Ear pads, headband padding and the cable are described as field-replaceable by the user.
Impedance (64 Ω), sensitivity (108 ±3 dB SPL at 1 V) and maximum SPL (123 dB) are all published, which helps when matching it to a mixer or headphone amplifier.
Sennheiser rates the contact pressure at approx. 6 N for a secure fit, and at approx. 297 g without the cable, comfort over long sessions is personal.
Check the supplied cable configuration: Sennheiser describes a coiled section near the earpiece, lists a 1.5 m cable in the box and approx. 1.55 m in the technical data. The separately listed straight cable is a replacement option. The transducer diameter is not stated.
The specification sheet lists this HD 300 PRO configuration without ActiveGard. Switchable ActiveGard hearing protection belongs to the separate HD 300 PROtect, article 506898; it is distinct from the unresolved active noise-cancellation claim.
Exact configuration: 508288 · HD 300 PRO (not HD 300 PROtect) · wired
23 specifications in 6 groups. Values are manufacturer specifications unless a row says “Measured result” or “Calculated from cited specifications”.
Approximate, without cable.
The box list names a 1.5 m cable; the technical data gives approx. 1.55 m. A replacement straight cable is listed as a spare part.
The spare part listed on the page is the 'HD 26/300 PRO - Straight Cable'.
Approximate; the box list names the cable as 1.5 m.
The reviewed exact sources do not explicitly establish battery life or a whole-device no-battery operating requirement. A wired connection, omitted charger or Battery included N does not establish not-required.
SourceVoltage reference (dB/V), not dB/mW.
Sennheiser does not state the transducer diameter on the pages and specification sheet read.
No level tolerance is stated.
The datasheet labels this 'Power rating'; the product page lists the same figure as 'Power consumption (Amp)'.
The reviewed exact sources do not explicitly establish active noise cancellation presence or absence for listening. Preserve separately documented microphone noise reduction, closed construction or passive attenuation; none negates active ANC.
The reviewed exact sources do not explicitly establish microphone presence or absence. Omission from package lists, optional microphone accessories and stereo audio pin diagrams do not establish microphone=false.
Not active noise cancellation or certified hearing protection.
Relative humidity up to 90%.
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