The sound is neutral and balanced, with an emphasis on the midrange, making it top of our list of the best Sennheiser headphones. They performed excellently in our detail retrieval tests and have a vast soundstage for a closed-back headphone.

Accuracy for monitoring purposes is excellent, with a slight exception in the artificial leaning bass, which we will discuss in a second. They ruthlessly reveal headphones and shine the microscope on poorly mastered or low-bitrate music, so pair your source files and components well with these headphones.

The Highs

The treble is extremely clear and detailed, with a fantastic extension. This is essential to how the HD820 can create such a massive soundstage. Contrary to what many people believe, good treble is the key and not bass.

If you are coming from a more mellow and laid-back tuning, the top notes may be jarring at first, but give your ears a few days to burn in, and I assure you it will be hard to return to a headphone with less superior performance.

Midrange

The sound focuses on the midrange, and it’s a very accurate and unflavoured tuning that doesn’t add anything in terms of warmth. They sound very similar to my reference speakers in how they are noticeably forward. I would ultimately say that they are very transparent in the midrange.

I like this because it gives me a lot of room to play with EQ presets, which are incredibly responsive. Again, its detail and space are the focus, but note decay from strings was also the top draw.

The vocal sound is open and airy, with outstanding clarity and depth. It has a superb midrange and one of the best I have heard in a closed-back design.

Bass Performance

The low end is right, detailed, and responsive. It impacts very hard when required, and the significant drivers can move a lot of air. After having used the Focal Stelia for a couple of weeks, I come to this review, and there is a noticeable difference in how each handles distortion. The bass is perfect for a closed-back. Let me explain.

What I am about to say is less a criticism of the headphones and more a criticism of what I have heard other reviewers mention about these headphones. 

Consistently, I see comparisons with the HD820 compared to open-back headphones, and you just aren’t going to get me to do that. Its fundamentals are flawed to make such comparisons other than saying, “For that price and if it suits your use scenario, consider open-back designs such as xx.” The person buying a closed-back headphone is likely aware that there are fundamental differences in how they will present the sound.

I understand the fundamentals of what people are saying. The bass sounds significant, impactful, and refined, just not as clean as those open-back models. When looking in closed-back headphones, wherever I look, there seems to be a trade-off. X has better bass, Sennheiser has better soundstage and treble, and so on and on and on.

In my eyes, only one closed-back headphone solves the problems and is fantastic in all areas, and that’s the Focal Stelia, which costs roughly twice the price. 

I believe the Stelia handles things so well because of the crazy internal structure of the foam that lines the inside of the earcup. It catches the sound before it gets bounced back and allows the Focal to control the sound without worrying about reverberation distortion. The Sennheiser has that glass back; as we know from the speaker world, hard surfaces are a big no-no. 

That said, the sound is fantastic on the HD820, and I doubt many people seeking a closed-back headphone will ever find a reason to complain. I would put them in my top 3 all-time favorite CB headphones based on that insane huge soundstage alone.

Conclusion: A top closed Headphone

The recommended retail price of the HD820 is around $2400. That is the price that this headphone was evaluated at for this review. It’s a lot of money, so obviously, they will be out of reach for many people, but they offer something unique in how the soundstage is similar to an open-back headphone. 

They are comfortable wearing headphones all day and are ruthless in revealing details. If you are willing to go for an open-back model, you can have more performance for a little less money, but then you lose the versatility of where and how to use closed-back designs.

Sennheiser HD820 official webpage

Update 2025: I think the HD820 at this point is are testament to what Sennheiser created in that its longevity seems everlasting. Mine have held up without any issue over the years, and I expect them to keep going strong. In fact, they are pretty much a staple in the rotation, outlasting others. I think the whole headphone space has gotten a bit crazy with lots of new materials being used, yet improvements to sound tapered off some years ago. With that, the strange thing about the HD820 is that with the price actually decreasing over time and the competition getting more expensive….. plus…. You know, inflation, the HD820 now actually represents very good value as well as exceptional performance for a high-end workhorse headphone.