I do not own the HE-400i, But I have owned the HE-560i and that has been for a long while it seems now. I own the HP-150 as well which is a very good closed headphone I recently did a comparison to the Oppo Pm-3 which goes for twice the price. The treble on the He-560 you may know is airy, detailed, articulate, and has great tonality. The Hp-150 from a far lower price point is a great closed headphone with quick bass and decent prat, mid range is neutral and still very good, treble is airy for a closed headphone and detailed. I have to say that the Oppo pm 3 does midrange really well and has a nice tone, but as far as treble, and sound stage go to the HP150 as it is one of the best sound stages and overall detail across the frequency I have heard in the price range.