Well to be fair Questyle marketed the 400i as a
DAC with Headphone Amplifier, so i think it is a little bit misdirected if you put the blame on Questyle.
If there is enough demand, maybe in the future they will transform from a DAC company to a Headphone Amp company?
After owning this thing for more than a month, I can safely say that i am really happy with this purchase
Sound wise it delivers all what i am looking for : Wide soundstage, airy with black background and good detail retrieval. It is definitely neutral and a little bit revealing, but some poorly mastered tracks are still fit for listening through my MH334. The 400i complements my full bodied 334 really well, listening to classical pieces now feels really satisfying with accurate timbre and good micro details. My complaint is just that it hisses with my IEMS (SE on higher volumes and BAL on any volume) and it runs really hot when i am not using the aircon