The 400i treble when paired with the A5 makes me dizzy. I sound tested both the fidelio X1 and He 400i using the A5 amp and e10k dac at audiohack.net's sound test and tried to match the volume as clsoe as possbile. The X1's frequency Responcse at 10hz>>200hz is better and starts producing at 20hz, while the He 400i starts at 30hz so why are most reviews stating that the HE 400i has better bass reach? whaaaaaaaaat???? The 400i is a little bit better in the high freq but not much.