I shifted from old jh13 to new jh16, the 16 is warmer, with a bit more mid-bass, so the vocal is much better now. The overall sound is thicker with more layers but not as clean as the jh13 due to some extra mid-bass, but its very minor difference. The overall signature is not that far apart. If u don't like vocals on jh13, it's a worthwhile upgrade.
Have been rather curious about the freqphase improvements.
It seems the JH16 is now closer to the Heir 8A signature. The added warmth does tend to "mask" the details somewhat although the details still shine through well.
i still enjoy the JH13 very much and the pairing with ibasso DX100 is just sublime.