I had the problem about a cable connection on HEM8. However hard I tried, I couldn't connect the high-end OFC cable to drivers. The cause of the problem was 2 pin jacks of the drivers. They are too tight. I connected another 2 pin cable (which is not the included one with mic) and disconnected it again and again until it gets smooth. Then, I finally got the high-end OFC cable connected! It is not the best solution of this kind of problem, for there is always risk that jacks or plugs are broken.
Besides HEM8, I bought HEM2 and EDC3 before, and love them all. The sound quality of the HEM series is, I think, competitive with famous earphone series, such as Westone's W series or Sony's XBA series. I hope NuForce will improve quality control and keep developing HEM series.