Sennheiser HD 400 Pro review: Supreme fidelity, stereo separation, and comfort

Sennheiser’s lineup of pro audio headphones starts at incredibly affordable prices and wanders into moderately expensive territory. The company’s new HD 400 Pro model, at £219, is somewhere in the middle of that scale. Designed for comfort and accuracy, they are aimed at producers, content creators, and those who just enjoy listening to music on high-quality kit.

• READ MORE: Erica Synths Matrix Mixer review: Truly experimental and radical patching

Why headphones?

With more people than ever producing on laptops or mobile devices, a reliable pair of headphones is vital if you want to take full advantage of your setup. You may well have a solid pair of speakers, but you’ll need headphones for mic recording, checking mixes, working at night, and working in different locations or on the move. As impressive as wireless headphones have become, those relying on Bluetooth have too much latency to be useful for live recording. Throw in the fact that they also compress audio before sending it to the phones, and it’s evident that wired models still rule the roost for studio and recording use.

Sennheiser’s HD 400 Pros are lightweight at 240g but feel well-built, with few moving parts, so they don’t flap around as some models can. The headband is adjustable, and the ear cups can flex inwards slightly to suit the shape of your head. These are very comfortable ‘phones, with the circumaural ear cups padded in velour and the headband sporting soft padding. When worn, they grip your head firmly but comfortably and are excellent for long sessions, neither fatiguing nor overheating your ears.

Get connected

The headphones come with two detachable cables and a 3.5mm to 6.3mm adapter. The 3m cable is coiled, and the 1.8m cable is straight, suitable for being further away from or closer to your mixer or interface, respectively. The connection is on the left ear cup, and it’s a shame there isn’t one on the right, too, as this offers the greatest flexibility when trying to keep cables out of the way. There are no extra bells and whistles like wireless or microphones on the cables – these are purely for wired listening.

Internally, they use specially developed 120-ohm transducers that sit at a slight angle inside the cups to create a triangular listening position akin to how you would experience sound through monitor speakers. This doesn’t mean there’s anything unnatural about the fit since the angling is done inside the cups themselves. The phones are open-back, which, in addition to helping prevent overheating during long sessions, means they don’t experience the boxiness that closed-back models can exhibit.

Open all hours

An open-backed design is common among reference headphones since it delivers the most accurate and neutral reproduction possible. It also means there is some leakage, especially at higher volumes, as sound can escape rather than being contained inside. So for monitoring during recording from a microphone, say vocals or acoustic guitars, it’s worth being aware of this.

The flipside is that they are extremely accurate in their reproduction. They exhibit superb stereo separation with a wide frequency response of 6Hz to 38kHz and low distortion even at high SPLs. Panned sounds that aren’t particularly obvious on other systems suddenly become pin sharp. They’re exceptionally revealing, making the layers of a mix clearer and more identifiable. Listening to recorded tracks from different eras makes the various mixing and mastering techniques more evident than ever.

Roots Manuva’s Run Come Save Me, an album that is 20 years old yet somehow still sounds like it has come from the future, gives up its mix secrets as the dubby electronics and punchy vocals skitter from the drivers. Nas’s 2021 album Magic sounds gritty and urgent, and Slowthai’s Feel Away sounds soulful and balanced despite its bass-heavy production. At the other end of the scale, John Martyn’s Solid Air reveals every breath and fret noise in the recording.

Open soundstage

There can be a misconception that more bass is automatically a positive thing for headphones, but this isn’t the case during mixing and mastering. Here, you want transparent and neutral reproduction because it means what you’re hearing is what’s really there. Get it right on neutral-sounding kit, and it will sound good on the near-infinite variety of devices on which it will be listened to. The HD 400 Pros are beautifully balanced and revealing across the entire soundstage. Bass, in particular, is solid but measured, not booming or overwhelming – the kind of bass response that you need from reference headphones.

Sennheiser also touts the dearVR MIX plug-in, which uses spatial audio technology to recreate different listening environments when mixing or mastering. It supports the HD 400 Pros, meaning if you use it, you can be sure that their characteristics are being compensated for as you mix. It costs £90, though a free trial version is also available.

Wrap up

These are excellent reference headphones for mixing and mastering and also for tracking with the aforementioned caveat about leakage. They’re supremely comfortable and offer an astonishing level of clarity and separation, especially considering their reasonable pricing. Closed-back models might offer more bass and a punchier overall sound but not the accuracy on offer here. If you’re serious about production, not to mention just enjoying listening to recorded music at its best, they’re a definite contender for your money.

Key Features

• Open-backed design
• 120-ohm angled transducers
• Circumaural velour ear cups
• Frequency response 6Hz – 30KHz
• SPL 110 dB
• Two detachable cables
• Special polymer diaphragm
• Optional spatial mixing plug-in
• 6.3mm adapter
• 240g weight
• £219