Every earphone here gives 35 to 42 dB of passive isolation, so you hear detail at lower, safer volume. The ER2 pair is the entry point, with one dynamic driver per side that needs no amplifier, so a phone drives it directly. The ER3 pair moves to a balanced armature driver with higher sensitivity, so portable listening needs less volume. The ER4 pair tops the earphones, with channels matched within 1 dB, so voices hold steady placement in the stereo image. Music Pro is an electronic earplug for musicians.

• Start here. The ER2SE suits a first buyer plugging into a phone, since it needs no amplifier, and the ER2XR suits one who wants extra bass.
• Sweet spot. The ER3SE costs only a little more than the ER2 pair and gives a commuter an easier drive from a phone at lower volume, while the ER4 models mostly add tighter channel matching.
• All in. The ER4SR is the top of the earphones and priced a modest step above the ER3 models, an extension of that line whose 1 dB channel matching keeps instruments steady in the stereo image.