Sennheiser IE 400 PRO

Scope of delivery and appearance

In my opinion, the scope of delivery for the IE 400 Pro is quite impressive. The transport case has a resistant surface made of fine nylon, sufficiently hard lids and, as well as an accessory compartment, a practical, integrated cable tidy. In addition, a cleaning tool is included as well as a gold-plated, 6.3mm jack plug adapter. Instead of the enclosed five pairs of replacement earpieces tumbling wildly in a bag, they are neatly arranged on a small rail. Even the sizes are clearly readable. That’s what I call handy!

The Sennheiser IE 400 Pro has two versions: “clear” and “smoky black”. Only the “smoky black” colour was available for testing and, in this model, the in-ear housings are slightly transparent. The appearance of the button headphones is simultaneously solid and modern.

Technology

The driver of the IE 400 Pro, which measures just 7mm, uses a method that Sennheiser calls “TrueResponse”. It should allow a flawless, distortion-free sound and an ultra-low total harmonic distortion of 0.08%. I am particularly excited about the bass performance of this small membrane. The air exchange in the chamber of the movable magnet system is ensured by three ventilation channels, and an absorber with two chambers serves to reduce level peaks that can occur due to cabinet resonances.

With their maximum sound pressure level of 111.5 dB / SPL, the IE 400 Pro is slightly louder than the smaller IE 40 Pro model. At 15.9 Ohm, the average impedance we measured is as low as it should be for stage monitoring. Their audio transmission range covers the frequencies from 6 Hz to 19 kHz, representing an extended bass response and a slightly limited treble image (at least on paper). Compared to the smaller IE 40 Pro model, the frequency range is still significantly extended. In terms of weight, the earphones including cable are a standard 18g.

Wearing comfort and handling

The robust workmanship of the in-ears allows them to survive drops and knocks. The plugs of the interchangeable cable are easy to remove and yet hold firmly and securely, so they are well protected against accidental removal. The bendable wire at the end of the lead provides just the right resistance to stay in shape, but is soft enough to effortlessly conform to the shape of the ear. Their comfort is exemplary, even with vigorous head movements. Because of their ergonomic design, the IE 400 Pro fit optimally in the ear and sit well when in place.

The included earmolds are made of silicone and viscoelastic memory foam, making them pleasant to wear in the ear. According to the manufacturer, their impact on the attenuation of external noise should amount to 26 dB and is therefore on a par with the smaller IE 40 Pro model. I really like that the position of the earmolds is adjustable. Depending on the desired sound pattern and attenuation, they can be positioned deeper or less deeply in the ear canal. All earmolds come with a coarse grid cross, which prevents foreign bodies from getting inside the inner ears. In addition, all pads are equipped with cerumen grilles, which also deter finer foreign bodies.

Lightweight, the in-ears can be worn comfortably over a longer period of time. In addition, the cable length of the earphones is 1.20m, ideal for hiding the cable unobtrusively and safely under clothing without too much excess length. Because of these features, the IE 400 Pro also get the thumbs up from me when it comes to stage suitability.

Soundstage

The IE 400 Pro is supposed to deliver a studio-quality dynamic sound that is punchy, detailed in the treble and transparent in the middle, yet still “warm”. Talk about lofty claims! In fact, these in-ears deliver rich bass that reaches down into the low bass range and creates a differentiated “thrust” without booming. The IE 400 Pro is also a good choice for high frequencies. The sound here is relatively wide, rich in detail and supporting both stereo width and depth gradation well. According to Sennheiser, resonance peaks are a thing of the past due to the design of the in-ear enclosures. In practice, there are no frequency ranges that interfered with my listening to the extent that I noticed too much overemphasis due to resonance. However, as with the IE 40 Pro, I still notice the mid-range. From my point of view, they lag behind the quality of the rest of the sound, as they tend to hiss depending on the production being listened to. This mainly affects the speaking voice and vocals with sharp s-sounds. But also listening to guitar-heavy music mixes can be exhausting over a longer period of time.