I originally purchased my JH-13s in January of 2012 and loved every moment of listening to them. A couple of weeks ago, I sent mine in for service due to issues with dirty filters affecting sound quality and the fit gradually became uncomfortable. I sent them in with a new set of impressions and they took care of the service and refit free of charge. When I got my package back from FedEx, FedEx had smashed the shipping box, which in turn smashed the Otter Box that came with my JH-13s. FedEx claims that they are not responsible for damage to contents of packages and was no help to me. I sent JH Audio an email about it and they've been helpful with finding me a replacement.
From a sound signature perspective, my JH-13s have always been my favorite IEM. However, since I got my refit back, the sound signature has significantly changed, to the point where it is uncomfortable to listen to. I'm not great at describing sound, but there is certainly a new prominence in high range. I wouldn't say it is sibilant, but it certainly seems edgy, and every last bit of recording static/ noise comes in with an exaggerated quality. Some songs seem okay, but I can't even make it through London Grammar's Strong without taking off the headphones.
I noticed a difference in the positioning and implementation of what I believe to be the high frequency armatures. Before, the high frequency armatures were actually placed in the canal, while they're set back now. What concerns me is easily visible in the photo below. On my old pair, a soft plastic tube accompanied the bores all the way to the tip of the canal on both bores. Now, only the bore for the low/ mids has the tube accompanying bore to the tip. The tube in the bore for the highs only extends about 2 mm past the filter, leaving the remaining 4 mm of the bore wider and exposed to the acrylic of the shell. I'm wondering if this is causing some sort of odd harmonics.
...I'll be giving JH Audio a call on Monday to figure this out.