Sound Quality
Studio headphones are supposed to have a neutral sound signature so they can be effective for their intended application. The problem is no one really knows what neutral is. Perceptibly, neutrality seems to be having a flat response from bass to right around the middle midrange, before naturally rising as it heads towards the highs.
My problem with studio headphones’ tuning is that most of the time they have elevated treble frequencies producing this harsh and bright sound. Now, I am no studio pro but if the intent is to find flaws in the mix and make sure the balance is right, then I wouldn’t say an elevated treble is ideal.
The HD400 Pro thankfully doesn’t have it. To my ears, they have what I would call a balanced tuning. Good sub-bass extension which I think is better than the HD6xx line (I did have the 660s to compare). It has a mild bass accentuation and a linear, perhaps slightly forward upper midrange that gives more weight to female vocals. The drawback of that is it can have that slight honk and nasalness for tracks that token those frequencies.
And I’m perfectly happy with the treble quantity of these headphones. Neither harsh nor sibilant and more importantly, it’s not like listening to a pair of razor blades like the stock sound of the Samson SR850. It does have a good extension past 10khz as well without being overly airy. It doesn’t have the smooth & effortless resolve that the HD660s has but that’s not something the application requires. Plus, the 660s is almost double the price of this headphone so there’s that as well.
Soundstage and imaging aren’t spectacular. I find the stage to be smaller than an average open headphone and there’s a strong center image as well. I would say the forward midrange presentation is the culprit here.
The headphone’s ability to retrieve detail is ok for the price and type. Not class-leading for its price or anything like that. From memory, it is quite a bit better than the ATH-M50x which has a more uneven frequency tuning relative to the HD400 Pro. Though it still does fall on the dull side when compared to again the HD660s, and higher-end Audeze and Focals.
The HD400 Pro is an efficient headphone just like most of the studio cans I’ve tried. As it is a moderately high impedance headphone at 120 ohms, it does scale a bit with an amplifier. I thought the bass sounded tighter and the overall presentation snappier when paired with the Monoprice THX 887.
Conclusion
Overall, the HD400 Pro is a more than capable monitoring headphone. It’s got a good frequency tuning and extension, the build quality is great and it’s comfortable. My girlfriend used this for video editing and she said it was great. Much better than her wireless noise canceller. 😀
I don’t have any other studio headphones in the house so all I can do is compare from memory. The HD400 Pro, as a whole, is better sounding than the ATH M50x, the AKG K240 Studio, the Samson SR850 & the Beyerdynamic DT880. All of which I have either heard or personally owned in the past.
For music listening, it’s ok although I think there are better options in this range, or if you’re willing to add a bit more namely the Hifiman Sundara, and Sennheiser’s very own 6xx line (HD600, 650, 6xx). The Audeze LCD-1, though I have not heard yet, is another one that seems to be marketed similarly to the HD400 Pro.
I find the HD400 pro to lack the smooth resolve and nuance of those headphones with it sounding a little on the dull and edgy side of things. Yes, that is 100% subjective (call it audiophile BS if you will) and can differ from person to person. But you don’t need that for studio applications. What you need is a headphone that tells you the flaws of the tracks, how balanced it is, and something that is sturdy and you can use for hours. The HD400 Pro confidently checks those marks. The only thing it doesn’t is good passive noise isolation which can be a dealbreaker if your work environment requires you to have one.
The Sennheiser HD400 Pro is available on JB Music stores and you can find more information about it here.