I have a pair of expensive in-ear monitors (earbuds). Each side utilizes six balanced-armature drivers and a passive crossover.
The right side is quieter than the left side. The headphone wires are detachable, so measuring across the mini coaxial port where the headphones connect to the cable, the right side's internal resistance is 15.60 ohms while the left side is 15.16 ohms. This imbalance in impedance might explain the imbalance in volume between each side. In Windows and Android software I can choose to increase the volume of the quieter right side. I have to increase the software's volume slider by 6dB in order for both sides to feel balanced.
Normal headphones have matching impedance on both sides. Something inside the right side is causing an increase in impedance and all the solder joints still seem solid, so I think the issue may be something internal to one of the six drivers. The 6dB difference is simply what the audio-control software in Windows and Android say I need. It is not actually the difference measured at the audio ports of the headphones.
You can see photos here:
Would I be able to take a headphone cable and on the left side solder a 0.45 ohm resistor inline to balance out the impedance of both sides, and thus fix the volume balance issue?
Would adding a resistor affect the quality of the analog signal reaching the drivers? Would it change the phase or timing of the signal, causing weird imbalances in the music coming out of the headphones?