Sennheiser HD 550 Open-Back Wired Headphones (International Version)

Of the three open-backs in this family, the HD 550 carries the highest impedance — 150 ohms — and the widest quoted frequency response, 6 Hz to 39.5 kHz. The body still weighs 237 g and keeps the synthetic velour pads and metal-mesh earcups of the range. If you already own an amp, or plan to buy one, this is the model in the trio that rewards the hardware most.

Key features

150 ohms, built around a proper source

At 150 ohms it is the highest-impedance model here, rated at 106.7 dB / 1 V RMS. Higher impedance makes a headphone less sensitive to a source's output impedance, so it behaves more consistently across different amps; the cost is that it wants more voltage, and driven straight from a phone it will feel short on both volume and dynamics. This one assumes you have a front end.

6 Hz to 39.5 kHz response

Sennheiser quotes 6 Hz at the bottom and 39.5 kHz at the top, the widest figures in the group. In practice what happens below 20 Hz shapes the decay and sense of space rather than producing audible bass notes, but the low-end extension does let large-scale orchestral and electronic material spread out convincingly.

Metal-mesh open-back earcups

The same high-grade metal mesh open design as the rest of the range gives an airy stage and clear separation between instruments. It also means zero isolation and audible leakage — worth keeping in mind at night in a shared flat. That is the price of the sound stage, not a defect.

Detachable cable and serviceable parts

A 1.8 m detachable cable with a 3.5 mm plug and a 3.5 to 6.35 mm adapter covers both amps and interfaces. Sennheiser lists compatibility with HD 500 range accessories and replacement parts, so pads and headband can be renewed instead of replacing the whole headphone.

Specifications

Who it's for

• Listeners who already have a USB DAC/amp or a desktop amp and want a headphone that can use the voltage.
• Classical, jazz and large-ensemble listeners who care about low-end extension and stage depth.
• Anyone who wants a light 237 g headphone without dropping down in specification.
• Who it isn't for: phone-only listeners with no plan to add an amp. At 150 ohms a phone output will run out of steam, and as an open-back it leaks too much for the office or the street.

Warranty and delivery

International version · 10-day exchange for faulty units · 100% brand new · viewing by appointment at our Kwun Tong shop. Full terms on the warranty policy page.

Non-TV items ship by SF Express freight-collect (the customer pays the shipping fee), or you can collect at the Kwun Tong shop free of charge, 11:00–19:00. For any other courier arrangement, or delivery to Macau, message us on WhatsApp. Full terms on the shipping policy page.

FAQ

Does 150 ohms mean an amp is mandatory?

Not technically, but we do recommend one. At 150 ohms with 106.7 dB / 1 V RMS, reaching a given volume needs more voltage than a low-impedance headphone does, and phone or laptop jacks usually hit their ceiling first. A modest USB DAC/amp is enough to solve it.

HD 550 or HD 505?

The real differences are impedance and response: the HD 550 is 150 ohms and 6 Hz–39.5 kHz, the HD 505 is 120 ohms and 12 Hz–38.5 kHz. Both weigh 237 g and both are rated under 0.2% THD. Take the HD 550 if you have an amp and want the deeper extension, the HD 505 if you want the easier load.

Is an open-back practical in a small Hong Kong flat?

It depends on your room. Open-backs isolate nothing, so traffic and air-conditioning noise come straight in, and quiet evening hours suit them best. If you share a living room or listen in cafés, a sealed or ANC model is far more practical.

Related products and guides

• Sennheiser HD 505 Open-Back Wired Headphones — the entry point in the same family
• Sennheiser HD 560S Open-Back Wired Headphones — the other open-back option
• All headphones and earbuds
• Parallel import vs licensed goods: the full guide
• Warranty policy (10-day exchange for headphones, cameras, mics)
• Shipping policy