Hifiman HE400se

The Hifiman HE400se offers an impressive audio experience, particularly for those looking to explore planar magnetic headphones at an accessible price point. 

Build and Comfort

Headband: The headband is one of the weaker points of the design, lacking the comfort and durability found in higher-end models. However, it's functional for shorter listening sessions.

Pads: The ear pads are good quality, though some people with rather large ears might find the internal space a bit more limited. Despite this, the HE400se forms a better seal around the ears compared to teardrop-shaped alternatives for smaller heads.

Weight and Clamp Force: The headphones are relatively light, and the clamp force is gentle, making them comfortable to wear for extended periods. However, the loose fit might be less ideal for those who prefer a snug fit.

Audio Quality

Treble: The treble is fast and energetic, delivering a lively sound without feeling cheap. There is a noticeable treble peak, which adds brightness but can be sibilant on certain tracks.

Bass: The bass is fast with good depth, though it doesn’t hit particularly hard. The HE400se leans towards a warmer sound, providing a rich, engaging low end without overwhelming the mids.

Tonality: The overall tonality is somewhat dry, which might appeal to those who prefer a more neutral sound. The headphones offer good detail retrieval for their price, but they may lack the fullness and richness found in more expensive models.

Imaging and Soundstage: Imaging is precise, allowing for clear placement of instruments and vocals. However, the soundstage is rather more on the narrow side, with vocals feeling a bit confined. But for its price it is really doing a great job. 

Amplification

Power Requirements: The HE400se is more difficult to drive than some other models. To get the best performance, an amplifier is highly recommended. Without one, when driven directly from a laptop or phone, the sound can come across as thin and lacking in power.

Price

The price of these is about 129 €~. 
That is a very good price for the audio quality you are getting. 

Conclusion

The Hifiman HE400se is an excellent choice for those seeking to experience planar magnetic technology without breaking the bank. While the headband could be improved and the soundstage expanded, the fast treble, deep bass extension, and overall detail make these headphones a standout option at their price point. Just be sure to pair them with a decent amplifier to unlock their full potential.