The Sennheiser HD 400 Pro are a pair of professional master headphones. They’re the first pair of rear-facing headphones in the company’s Pro lineup, which until now has only had closed-back headphones.
The HD 400 Pro is essentially Sennheiser’s HD 560S with a few tweaks, none of them in sound. Compared to the 560S, the HD 400 Pro has a slightly modified design and an extra cable in the box, and for that, they cost a little more.
Design
The design of the HD 400 Pro is similar to the HD 560S, which itself is similar to many other HD 500 series headphones.
The difference between the HD 400 Pro and the HD 560S comes down to specific details. The silver Sennheiser logo on the side of the headset is embossed in black. Similarly, the Sennheiser wordmark on the head is now slightly larger, but has been turned black.
Other than that, the two are essentially the same headphones. The headphones have wide earcups with enough depth and width to accommodate all but the largest ears. The back is covered in black mesh and the headband has soft foam padding.
Other than the grille, the rest of the earphones are made entirely of plastic. This is the case with most Sennheiser headphones and although they don’t immediately feel premium, they are known to be durable and last for decades of use. As the Sennheiser pads become flat after two years of use, which affects the sound, the only thing that needs regular replacement is the earcups.
The headphones don’t have a lot of chatter. You can adjust the length of the headband and that’s it for the most part. The headphones have a very slight twist in both directions. That doesn’t mean they don’t fit securely on your head, but if you feel like taking them off and putting them on your chest, that’s not happening. The headphones also don’t fold, which is good since they aren’t meant for travel and outdoor use.
There is a connector for connecting the cable on the left earpiece. The input jack is 2.5mm in size but more importantly it has a proprietary locking mechanism that makes it difficult to use any cable you have lying around.
Speaking of cables, the HD 400 Pro comes with two, a 3m coiled cable and a 1.8m straight cable. Both have a 3.5mm jack and a 3.5mm to 6.3mm adapter is provided in the box. In comparison, the HD 560S comes with a 3m cable with a 6.3mm jack. The more common 3.5mm jack on the HD 400 Pro cable should be handy for plugging directly into a computer, and the coiled cable helps move it around the studio without having to untangle the cable or need it under your chair.
You won’t find much else in the box. Obviously there is not even a carrying case or bag as they are meant to be carried and not for indoor use.
Consolation
The HD 400 Pro are a comfortable pair of headphones. There is some clamping force but it’s never uncomfortable and helps keep the headphones secure no matter how much you move your head.
As mentioned earlier, the headphones are very large and comfortable. The material is soft and feels comfortable on the skin. The foam pad on the head is similarly flat.
Thanks to their plastic construction, the headphones are also lightweight and won’t introduce them to the head after some time. The direct cable is relatively thin so it is very light and does not pull the headphones down. It is clear that the coiled cable is heavy, but this is to be expected.
Performance
The Sennheiser HD 400 Pro are exceptionally well-tuned headphones. The sound is so neutral and accurate that it doesn’t sound like you’re listening to a pair of speakers, but just the main sound when recording. It’s like looking through a pair of colored glasses all your life and suddenly they become clear.
Bass response is incredibly neutral and precise, well into the low registers. This is not usually the case as open back headphones lack low bass extension, but the HD 400 Pro are somewhat immune to this disease.
The mid range is absolutely glorious. Voices have a wonderful clarity and intimacy to them. Instruments have amazing accuracy and timbral characteristics. Each instrument and sound source is unique in its mix of depth and volume.
Treble is where things get a little spicy. For the most part, the treble response is impressively precise and detailed, as is the rest of the frequency spectrum. However, the HD 400 Pro adds a bit more spice to the top, making certain sounds crisper. The sound is never tiring, but some bright recordings can be a bit harsh and long-lasting. Personally I don’t mind but your mileage may vary. Like the bass, the treble has good extension into the upper registers.
From a technical point of view, the HD 400 Pro has a very detailed and clear sound. The two 40mm dynamic drivers can get all the fine details in your music and recordings without being too up front about it. Although not the best I’ve heard, imaging and sound are excellent. Voices have good positioning around the head and there is good spaciousness in the mix. Not quite on the same level as the HD 800/HD 800 S but then again, what is?
The HD 400 Pro needs some zoom to get the best out of it, but I’m surprised at how much you can run from a laptop or even a smartphone. It’s not ideal and you should invest in a budget DAC/amp like the iFi Zen Air DAC or the Topping DX3Pro+ if you can, but you can get by with on board audio.
Being open-back headphones, they don’t get much isolation from ambient sounds, and they pump out just the right amount of volume. This may not be ideal for mixing or streaming purposes, so be sure to use the headphones in quieter environments during critical listening.
While overall I’m very impressed, I do have one complaint about the HD 400 Pro’s sound. My review unit seems to have some channel imbalance where the right driver sounds louder in a certain part of the frequency spectrum. It can be something with these headphones or it can be just one time. That’s hard to say, but all I can do is report a unit that was sent to me for testing.
The verdict
The Sennheiser HD 400 Pro ($250) are excellent headphones, as are the HD 560S ($200). The HD 400 Pro comes with a selection of cables that make it more practical and premium value, not only for studio use, but also for general purpose listening.
That latter part, for me, is where the HD 400 Pro excels. I’m not particularly sold on the idea of using headphones for mixing/teaching, let alone an open-back pair. However, the HD 400 Pro makes for exceptional general-purpose headphones for anything from music, movies, TV shows, games, podcasts, YouTube videos, and whatever else you can throw at them. It’s a very affordable way to add reference-quality sound to your setup, and one I’d recommend anyone spending under $300 go ahead with.