Sennheiser HD 400 PRO are open headphones, which the company has designated as studio headphones of the HD 400 PRO reference class. Outwardly, the novelty is practically indistinguishable from the Sennheiser HD 560S model.
Sennheiser’s engineers allegedly tried to combine lightness (weight without cable – 240g), accuracy (total harmonic distortion at a frequency of 1kHz at 90dB SPL – better than 0.05%) and comfort provided by comfortable velor ear cushions.
Sennheiser HD 400 PRO studio directivity is evidenced by their impedance of 120 ohms. It is unlikely that this impedance can handle any low-powered mobile source – on the other hand, the sensitivity of the novelty is 110dB such sources will like. However, judging by the presented photos, the manufacturer does not mind using the HD 400 PRO not only for work, but also just to enjoy the right sound.
The right sound is ensured by the speakers, according to Sennheiser, use “a special mixture of polymers” in their diaphragms. According to the developers, the magnet system is powerful and the ventilation system is efficient.
All this is aimed at deeper bass and reduced distortion. The location of the speakers also contributed to this – they are “turned upside down” to the ears. The overall goal that the company tried to achieve is neutrality and accuracy.
The kit with the Sennheiser HD 400 PRO included two cables at once: “straight”, 1.2m long, and spiral, stretching up to 3m, with a 3.5mm plug.
In the US, the Sennheiser HD 400 PRO headphones are already available for $250.