Sennheiser HD 400 Pro Review
Sennheiser HD 400 Pro Review
Sennheiser has long been a titan in the audio world, renowned for crafting headphones that span the gamut from consumer-grade earbuds to high-end audiophile gear and professional studio tools. Among their latest offerings is the Sennheiser HD 400 Pro, a pair of open-back studio headphones designed with mixing, editing, and mastering in mind. Launched as part of Sennheiser’s professional lineup, these headphones aim to deliver a natural, accurate soundstage for audio professionals while maintaining the comfort and durability needed for long sessions. Priced competitively at around $249 (as of their release in late 2021), the HD 400 Pro sits in a sweet spot between affordability and premium performance. In this review, we’ll dive into every aspect of these headphones—design, build quality, sound performance, features, and real-world usability—to determine whether they live up to the hype and Sennheiser’s storied reputation.
Design and Build Quality
At first glance, the Sennheiser HD 400 Pro exudes a minimalist, utilitarian aesthetic that’s unmistakably Sennheiser. The headphones are clad entirely in matte black plastic, from the headband to the earcups, with subtle black-on-black Sennheiser branding that keeps things understated. This lack of flash might disappoint those who prefer a more eye-catching design, but for studio professionals, it’s a practical choice—form follows function here. Weighing in at just 240 grams, the HD 400 Pro is remarkably lightweight for an over-ear, open-back headphone, a trait that bodes well for extended use. The lightweight construction doesn’t come at the expense of durability, though; the high-quality plastic feels sturdy enough to withstand the rigors of daily studio life, and the replaceable velour earpads suggest Sennheiser has longevity in mind.
The open-back design is the defining feature here, with large, molded grilles on the earcups allowing sound to escape freely. This isn’t a headphone for noisy environments or public transit—sound leakage is significant, and external noise seeps in easily—but that’s by design. Open-back headphones excel in controlled settings like studios, where their airy soundstage can shine. The earcups themselves are circumaural (over-ear), with soft velour padding that’s gentle on the skin. While the earpads aren’t the deepest, they’re spacious enough for most users, though those with larger ears might notice slight contact with the inner driver housing over time. The headband, also padded with velour, offers a moderate clamping force that keeps the headphones secure without becoming uncomfortable, even after hours of wear.
Adjustability is straightforward, with a notched headband that slides to fit various head sizes. The earcups have minimal swivel—enough to conform to your head but not enough to lay flat around your neck when off. This lack of articulation, combined with the absence of a folding mechanism, means the HD 400 Pro isn’t built for portability. It’s a studio tool, not a travel companion. Included in the box are two detachable cables: a 3-meter coiled cable and a 1.8-meter straight cable, both terminating in a 3.5mm TRRS mini-jack with a locking mechanism. A 6.3mm adapter is also provided for compatibility with professional audio gear. The TRRS connector, with its independent return paths for left and right channels, promises reduced crosstalk—a subtle but welcome touch for audio purists.
Sound Quality
The heart of any headphone review lies in its sound performance, and the Sennheiser HD 400 Pro doesn’t disappoint. Sennheiser touts these as “reference headphones” with a “natural and accurate listening experience,” and they largely deliver on that promise. At the core of the HD 400 Pro is a 120-ohm dynamic driver featuring a diaphragm made from a specialized polymer blend. Paired with a high-power drive magnet and a damping system for ventilation, this transducer is engineered for clarity, low distortion, and a wide frequency response—rated at an impressive 6 Hz to 38 kHz (-10 dB). While human hearing typically caps at 20 Hz to 20 kHz, the extended range contributes to a sense of precision and airiness that’s palpable, even if the extremes aren’t directly audible.
Bass
Let’s start with the low end. Sennheiser describes the HD 400 Pro’s bass as “deep yet clear and well-defined,” and that’s an apt characterization. The bass is controlled and detailed, extending low without overwhelming the mix. Unlike consumer headphones that often boost the low frequencies for a punchy, crowd-pleasing sound, the HD 400 Pro opts for neutrality. Sub-bass is present—think the rumble of a kick drum or the growl of an electronic bassline—but it’s never bloated or boomy. This restraint makes it easier to assess bass levels in a mix accurately, a critical factor for studio work. Compared to closed-back headphones, the open-back design lends the bass a more natural decay, though it sacrifices some of the visceral impact you’d get from sealed cans.
Midrange
The midrange is where the HD 400 Pro truly shines. Vocals, guitars, and synths sit comfortably in the mix, with a smooth, uncolored presentation that avoids harshness or recession. There’s a slight warmth to the mids, which some might attribute to the headphone’s overall tuning, but it’s subtle enough not to skew your perception of the source material. This neutrality is key for mixing and mastering—too much mid-forwardness can lead to overcompensating in the EQ, while recessed mids might hide details. The HD 400 Pro strikes a balance, delivering clarity and definition without sounding sterile or clinical. Instruments are well-separated, and the open-back design enhances the perception of space, making it easier to pinpoint elements in a busy mix.
Treble
In the treble department, the HD 400 Pro offers a crisp, airy quality that’s detailed without crossing into fatiguing territory. There’s a gentle presence boost around 5 kHz, adding a touch of sparkle to cymbals and high-frequency details, but it’s tastefully done—nothing shrill or piercing here. The extended treble response (up to 38 kHz) contributes to an open, spacious feel, though the benefits are more felt than heard. For long listening sessions, this tuning is a blessing; the highs remain revealing without causing ear fatigue, a common pitfall in overly bright headphones. Compared to Sennheiser’s audiophile models like the HD 650, the HD 400 Pro’s treble is a bit more prominent, but it’s still restrained enough for analytical listening.
Soundstage and Imaging
Thanks to the open-back design and angled transducers, the HD 400 Pro boasts an expansive soundstage that rivals many competitors in its price range. Sennheiser claims the angled drivers simulate the positioning of high-end studio monitors, and while it’s not a perfect replica of a speaker setup, the effect is convincing. Sounds appear to emanate from beyond the confines of your head, creating a wide, three-dimensional field that’s ideal for assessing stereo placement and depth in a mix. Imaging is precise, with excellent left-right separation and a clear sense of directionality. This spaciousness is a double-edged sword, though—while it’s a boon for studio work, it lacks the intimate, in-your-face energy some prefer for casual music listening.
Overall Tuning
The HD 400 Pro’s tuning is unmistakably neutral, with a flat frequency response that prioritizes accuracy over excitement. Total harmonic distortion (THD) is impressively low at <0.05% (1 kHz / 90 dB SPL), ensuring what you hear is a faithful reproduction of the source. This isn’t a headphone that flatters poorly mixed tracks or adds artificial warmth—it’s a truth-teller, exposing flaws and strengths alike. For professionals, this honesty is invaluable; for casual listeners seeking a fun, colored sound, it might feel too analytical. Sensitivity is rated at 110 dB SPL (1V RMS, 1 kHz), and while the 120-ohm impedance isn’t overly demanding, pairing it with a decent headphone amp or audio interface yields the best results—laptops and phones can drive it, but the sound doesn’t fully open up without proper amplification.
Features and Accessories
The HD 400 Pro keeps things simple, focusing on core functionality rather than gimmicks. The inclusion of two cables—coiled and straight—adds versatility, catering to both studio setups (where the coiled cable’s reach is handy) and more static listening scenarios. The locking TRRS connector is a thoughtful touch, ensuring a secure connection during use, though it limits third-party cable options. The 6.3mm adapter broadens compatibility with pro gear, and the velour earpads are replaceable, extending the headphone’s lifespan. Sennheiser also highlights compatibility with Dear Reality’s dearVR MIX plugin, a spatial audio tool that simulates different listening environments. While this integration is a nice bonus for mix engineers, it’s not exclusive to the HD 400 Pro and requires separate purchase, so it’s more of an ecosystem perk than a standalone feature.
Comfort and Usability
Comfort is a standout feature of the HD 400 Pro. At 240 grams, it’s light enough to wear for hours without strain, and the velour earpads and headband padding distribute pressure evenly. The clamping force is just right—secure but not constrictive—and the open-back design helps with ventilation, reducing heat buildup during long sessions. For studio use, this is a major plus; fatigue from heavy or sweaty headphones can derail a productive day. The trade-off is the lack of noise isolation, a non-issue in quiet environments but a dealbreaker for recording near open mics or in noisy spaces. The cables are lightweight and unobtrusive, though the coiled option can feel bulky if you’re moving around a lot.
Comparison to Competitors
How does the HD 400 Pro stack up against rivals? Compared to the Beyerdynamic DT 900 Pro X ($299), another open-back studio headphone, the Sennheiser offers a more neutral tuning versus the Beyerdynamic’s slightly brighter treble. The Audio-Technica ATH-R70x ($349) provides a wider soundstage but feels less refined in the mids. Sennheiser’s own HD 560S, a consumer model with near-identical internals, is cheaper (around $200) but lacks the coiled cable and pro branding—some argue the HD 400 Pro is a rebranded HD 560S with minor tweaks, though Sennheiser positions it as a distinct studio tool. Against the venerable HD 650 ($399), the HD 400 Pro is less warm and more analytical, trading some musicality for precision.
Pros and Cons
Pros
- Neutral, accurate sound ideal for mixing and mastering
- Expansive soundstage and precise imaging
- Lightweight and comfortable for long sessions
- Durable build with replaceable earpads
- Versatile cable options
Cons
- Open-back design limits use outside quiet environments
- Minimal portability due to non-folding design
- Requires amplification for optimal performance
- Subtle warmth may not suit those seeking cold, clinical analysis
Final Thoughts
The Sennheiser HD 400 Pro is a stellar addition to the brand’s professional lineup, delivering on its promise of natural, accurate sound in a comfortable, well-built package. For audio engineers, producers, and mixers, it’s a reliable tool that reveals the nuances of a mix without embellishment—perfect for fine-tuning tracks in a controlled studio setting. Its lightweight design and thoughtful features, like the dual cables and low-distortion drivers, make it a joy to use over long hours. However, it’s not a one-size-fits-all headphone. Casual listeners might find its neutrality underwhelming compared to bass-heavy consumer models, and its open-back nature restricts its versatility outside the studio.
At $249, the HD 400 Pro offers exceptional value, undercutting many competitors while matching or exceeding their performance in key areas. It’s not a revolutionary leap over Sennheiser’s existing models like the HD 560S or HD 650, but it carves out a niche as a purpose-built studio workhorse. If you’re in the market for open-back headphones that prioritize fidelity and comfort for professional audio tasks, the HD 400 Pro deserves a spot on your shortlist. For everyone else, Sennheiser’s consumer lineup might better suit your needs—but for the studio-bound, these are a triumph of function over flash.
