I am interested in FiiO's earphones. I am putting my Etymōtic on the back burner because I am getting tired of having various things fail on them. The quality is not what it once was. My other go to earphone is Shure. I have SE215 going strong that are 10 years old is telling they just don't sound as good as the Ety's. So this time I upgraded to the Shure SE425 Pro, about the same price as the ER4SR's. The are a 2 way with a pair of balanced armature drivers. Their cables are industrial strength and a little hard to deal with so I ordered the FiiO LC-RC Earphones/Headphone Cable with High-Purity Silver-Plated Monocrystalline Copper and 2.5mm/3.5mm/4.4mm Swappable Plugs. These are a standard MMCX cable and they will work on all earphone that use the standard MMCX plug. Etymōtic MMCX is a proprietary design. For a little more FiiO has one with pure Silver wires.
