Sennheiser HD 550 review: A confusing but strong addition to the HD 500 series

Another one?

Meet the new Sennheiser HD 550. It’s a curious headphone because just over a month ago, Sennheiser launched another HD 500 series headphone called the HD 505 Copper Edition. To further complicate matters, the two headphones have mostly the same design and even have the same driver. This begs the question: what is the difference and is there really a need for this new HD 550. Let’s see if we can find the answers to these questions.

The TL;DR version:

In many ways, the Sennheiser HD 550 has some of qualities of the first-generation HD 800, which should please listeners who prefer a more neutral and reference type sound.

Note: You can find the Sennheiser HD 550 on Lazada and Shopee, and the Sennheiser Online Store.

I suppose to find the answers to the abovementioned questions requires some understanding of Sennheiser’s product nomenclature. In a post on Head-Fi, Sennheiser explained that this is how one can identify and differentiate Sennheiser products.

This was what Sennheiser said:

The first letters classify the headphone at the widest part of the funnel: “HD” stands for Headphone, Dynamic, as it always has. IE is an In-Ear (dynamic), HE is Headphone Electrostatic, etc. This remains unchanged.

The next number (in this instance, “5”) places the headphone in a performance series: HD 500, 600, or 800..again, unchanged.

The numbers after that is where we are going to tighten things up.

x20 will be reserved for closed-back models (example: HD 820, HD 620S)

x50 and x00 will lean towards neutral tuning (example: HD 800S)

x60 will lean towards a warmer tuning (example: HD 660S2)

xx5 will, in most cases, indicate a retailer limited release in your market (example: HD 505)

Source: Head-Fi

Going by the above naming logic, it stands to reason that perhaps the HD 550 is the global version of the HD 505—seeing that the two are so similar and the HD 505 is supposedly a limited release. Lucky for us in Singapore, we get both headphones.

Physically, the only difference between the two is the accents around the headphone. The HD 550 has silver accents around the earcups, while the HD 505 features copper accents. The two share similar construction and material. Consequently, the design of the HD 550 shares the same strengths and flaws as the HD 505.

The HD 550 is remarkably light and comfortable, and its earpads can be easily replaced. This is helpful if they get worn in the future or if you want to experiment with different pads. However, one possible downside to this design is that the headband. It’s covered entirely by synthetic leather, which can be prone to peeling. If it does peel in the future, the entire assembly needs to be replaced.

Like the rest of the HD 500 series, the HD 550 uses a detachable cable which makes it easy for owners to swap cables in the future. The headphone requires a 2.5mm input, and the stock cable terminates in a 3.5mm plug. A 6.35mm screw-on adapter is supplied. These, along with a simple drawstring bag, are all the accessories you get.

Sennheiser is coy on the internal changes of the HD 550. However, we know it uses a 38mm dynamic driver—likely the same as the HD 505 but with a slightly higher impedance (150Ω vs 120Ω) and lower sensitivity (106dB vs. 107.9dB). And peering into the ear cups themselves reveals a different baffle design that appears to employ less restrictive filters. Interestingly, the drivers are made at Sennheiser’s Tullamore facility, where they also make legendary headphones like the HD 800 S and HD 650.

Unsurprisingly, the HD 550 sounds very similar to the HD 505. Its sound signature is best described as neutral and analytical. It’s clearly tuned to offer a listening experience that stays faithful to the material and with little colouration. With its neutral tonality, lightness of bass, and wide soundstage, it reminds me—in some ways—of the HD 800. No, the HD 550 can’t match the HD 800 for resolution or detail retrieval, but there are some similarities in their overall sound signature.

Against the HD 505, the HD 550 is the ever-so-slightly warmer of the two, thanks to its faintly stronger bass response and less forward upper midrange. But unless you are a seasoned listener and have the two headphones to compare one after the other, I doubt many can tell the difference. The distinction between the two really is that trivial.

One final point worth mentioning is that the HD 550, like the rest of the HD 500 series, benefits from better upstream equipment. It sounded noticeably crisper and tighter when I paired it with my headphone amplifier and USB DAC than when it was playing straight out of my MacBook Pro’s headphone jack. Having said that, the HD 550 is fairly sensitive can get loud enough even on the MacBook Pro.

Buying advice & final thoughts

Given how similar the HD 550 and the HD 505 is, it’s perplexing why Sennheiser decided it needed to have both headphones in its lineup. Even if you prefer the slightly bass-heavier sound of the HD 550, you could get away by picking up the cheaper HD 505 and then raising its bass response using EQ. Purists might disagree with this approach, but the pragmatist would rejoice. For context, the HD 550 is S$449, while the HD 505 is S$399—not a huge difference, but not an insignificant one either.

As confusing as the new HD 550 may be in the way it fits into the overall HD 500 series lineup, the takeaway is that Sennheiser’s has bolstered its entry-level open-back headphone lineup with another competent addition. Folks who wanted a slightly warmer and bassier HD 505 now have that choice with the HD 550.

But if warmer-sounding headphones are your preference, don’t forget Sennheiser’s legendary HD 650 and HD 600. These two open-backs have a warmer more intimate sound and have been well-loved for decades. The new HD 500 headphones are more accurate, but the HD 650 and HD 600 have a lush sound that’s very appealing. Crucially, their prices have come down significantly. Interestingly, the HD 650 is S$469 and the HD 600 is S$399, which closely mirrors that of the HD 550 and HD 505. 

Ultimately, readers should pick the HD 600 series if their preference is for a warmer and more lush sound, and the HD 500 series they prefer a more neutral and reference-like sound signature. Either way, Sennheiser’s offerings of affordable (relatively speaking, of course) open-back headphones have never been stronger.

Note: The Sennheiser HD 550 goes on sale on 14 April 2025 and you can find it on Lazada, Shopee, and the Sennheiser Online Store.