Still can't figure out why raising output impedance via serial resistor alleviates the distortion. Wish I knew output impedance of 71b. Emailed Ray.
Another thing that makes no sense is how etymotics is claiming you can turn the low impedance ER4p into the 100 ohm S model that sounds better, with a serial resistor.
Edited by SoundFreaq - 5/16/13 at 8:08pm