Finally got my JH16 Pro FP back from JH Audio, and have been listening to ZX-1/PHA-2 combo with it. I actually went through the entire Duran Duran Greatest Hits album - yeah, I am not necessarily proud of this - before moving on to my usual assortment of high res Jazz and Rock tracks.
To make the long story short, the JH16s proved to be a great match for the ZX-1. I guess this is true in general with the JH16s, but there was just a lot of "good" bass - not boomy, but just "meaty" and fast - with these earphones even when the ZX-1 was unamped. I think whoever thought the ZX-1 was a little thin on the low end side should definitely try it with the JH16 Pros... With the PHA-2 added to the chain, I thought there was a marginal improvement (soundstage, mid-bass) to the overall SQ, but I could definitely live with the unamped ZX-1 with the JH16s. The somewhat pronounced bass presence did not take away from other frequencies, and both the treble (good extension) and midrange (overall presence) were very much enjoyable.
BTW, the Yankees finally got Masahiro Tanaka, and maybe, just maybe, they won't suck like a vacuum cleaner next year...