This is not very difficult to drive, but benefits a lot from a good amp. Less powerful USB dongles may not be enough, but this shines with my E1DA 9038D. Are there better sounding headphones out there? Yes sure. But you will spend way more money for a little bit of gain. But that is just my opinion and the complain box is already full. The various iterations were the HE400s , the HE400i with the 2.5mm connectors , then the HE400i with the 3.5mm ones and now the latest HE400i 2020 version which is being reviewed here.

HiFiMAN HE400i 2020 Edition Review | TechPowerUp

The roughness of the response and mismatch between channels will make it more challenging to build an EQ.

SoundMAGIC HP1000 Review • The Outsider

I had this in the low gain setting mode at 73% volume. I used Fiio music player in pure mode, which converts all files to dsd. although just for fun I tried other stuff I felt that the fire M11 was more than adequate to produce decent sound out of the HE400i. The recording on the video embedded here uses the Fiio M11, for your reference. The Huawei Mate 10 has a sound signature of neutral-bright, sound quality far below the M3s, cranking the volume to 80-100 the sound of 400i is just decent compared to the SUNDARA, it sounds dry and thin to the point that male vocals doesn’t have sufficient body. I don’t recommend using it with smartphone alone cause you’ll get around 30 percent of its full capacity (soundwise). I know that I've made these sound like perfect headphones but they aren't......... some things I disliked about these are below**

HIFIMAN HE400se Review - Headfonia Reviews HIFIMAN HE400se Review - Headfonia Reviews

I decided to give a certain score to various aspects of HE-400i, 10 of these aspects refer to the sound, while few others refer to the non-sound related qualities like appearence, comfort, efficiency, value etc. All aspects have range from 1 (the worst grade) to 10 (the best grade). Virtually the perfect headphone (for the sound alone) would naturally be 100/100 in my scale book (haven´t heard such one yet Because of that I decided to give HE-400i two kinds of score. The first one is just for the sound alone and the second one is my overall score (it includes both sound related and non sound related aspects) of the product. Treble on HE-400i is reasonably extended with a gentle spike around 9-10 kHz, which for me provides just the right amount of sparkle. There is less treble energy on HE-400i than on HE-560 or DT 990 but a bit more than on LCD-2 or Oppo PM 1. Cymbals, percussions, organ or string instruments like violin sound detailed and clear. There is no exaggerated focus on treble (like on DT 990) which may result into analytical tonality and fatiguing sound. Some headphones somewhat artificially boost treble which can give a listener sense of ultra detailness but usually such headphones (like DT 990) have V-shaped sound and that is not my preference. On the other hand HE-400i doesn´t sound artificial in treble but quite natural, sufficiently detailed and smooth. Treble is well integrated with other parts into frequency spectrum and contributes to the balanced tonality of HE-400i. OK, there are headphones which have slightly more detailed and still perfectly natural treble, namely HD 800 and HE-6 (these two headphones have the best treble I´ve heard so far), but on the other hand HE-400i offers (at least for me) sufficient treble oomph without harshness or sibilance. Sibilance or treble harshness/hardiness may occur very very rarely and only on pretty bad recordings ( usually badly mixed, highly compressed remasters in mp3 format) On decent recordings, even on compressed, modern date music with poorer dynamic range, there is virtually no sibilance or excessive glare. I am sorry for a comparison to speakers, but my Dynaudio Focus 110A (1800 € expensive) are in no way so forgiving of poor recordings while Hifiman HE-400i is in that regard much more listener-friendly audio product. What already sounds harsh or overly bright on my speakers is still perfectly listenable on HE-400i. Among headphones HE-400i is more forgiving of bad recordings than DT 990, HE-560, HD 800 or HE-6. In my opinion it even rivals LCD-2 (fazored) and is only slightly inferior to Oppo PM1 in this regard. This is also one of the reasons why HE-400i has non-fatiguing sound and why I am giving such a high grade also in this section – 9/10. According to Hifiman, the HE400SE offers outstanding audio at a very affordable price. Superior sound and realistic spatial separation bring out the best in any source. Let’s find out if that makes sense.Mids: Oh. Thissss. This is amazing. The mids have a sweetness to them that is hard to describe, its unlike anything I’ve ever heard. The instruments are presented in a way that is just a joy to listen to! On Porcupine Tree’s song- My Ashes, the guitar sounds incredible and the imaging is very good. The vocals carried that sense of dark atmosphere which just stood out so much to me! And not surprisingly Steven Wilson’s songs are great on these. The Vocals and the instruments never sound congested, rather they flow. Green day is also amazing here. The guitar riffs have a sense of authority to them. On Diana Krall’s Let’s Fall in Love, her voice sounds intoxicating to say the least. I’m blown away each time I hear that song. Bjork and Carpenters also sound amazing! Blowing me away each time I put their songs on. Starting with the bass, the new release by Hifiman impresses from the first notes. Low frequencies are fast, accurate, full-bodied and refined.