Setup: USB-Type C to Type-A converter -> Apple Dongle/MOTU M2 (Both calibrated) -> TRRS Splitter -> Dynamic microphone -> IEC60318-4 compliment inner-ear simulator + Room EQ Wizard

The DX160 (0.3 Ohms unbalanced and 0.4 Ohms balanced) or Apple Dongle (0.1 Ohms) or the MOTU M2 (0.7 Ohm) will be used to drive the source for measurement.

Graphs are created with the following procedure:

1. Using white noise to reach 85dB(+-1.0dB) on Left channel. Maintaining same volume step in right channel
2. Resonance peaks are kept as close as 8.000Hz as possible (Consider this as a guidelines, the insertion peak might varies on some IEM like ER4S where I intentionally left a >10kHz insertion to emulate a deep insertion)
3. Microphone are calibrated using provided file from manufacturer
4. Soundcards are calibrated using either manufacturer files (if available) or by running a sweep with an external loopback setup using REW
5. Sine sweep are ran with Length = 256k and Sample rate of 48kHz with 1 repetitions
6. dB Scale: 60 - 110dB

All IEM are measured using silicone tips unless stated otherwise