Do headphone cables matter? In-ear microphones say no.

This is the videographic culmination of my Head-Fi threads in https://www.head-fi.org/threads/in-ea... [1] and https://www.head-fi.org/threads/conti... (post #8) [2]. This covers the use of in-ear microphones to measure the audio that ultimately reaches the entrance of your ears and determine whether headphone cables could possibly significantly change what the headphone outputs. My results came negative, consistent with my personal hearing impressions.

Raw measurements: https://drive.google.com/file/d/1YZTl...

This video, recorded on December 27, 2023, and edited on December 28, marks my having finally moved from the dreaded MS Video Editor to DaVinci Resolve 18 which presents a much more pleasant clip trimming experience. The video and audio were captured with my Samsung S21, whereby I've found that this cellphone's stereo audio can present a pleasant semi-binaural experience for headphone users.

See below for chapter timestamps:

0:00 Introduction
1:55 "What is sound?" Credit to the creator of https://www.desmos.com/calculator/hdq... for the square wave visualization. There are many online resources for understanding the nature of sound and signals as a superposition of waves.
4:04 On the relevance of phase response. "original *thread*"
4:47 Reasons for hearing cable differences
5:30 On frequency response measurements
7:09 Measurement methodology: in-ear microphones from https://www.earfish.eu/. More details in [1] and https://www.head-fi.org/threads/meze-... (post #5,152) [3].
8:32 On obtaining accurate phase response measurements and reducing noise floor. More details in [2].
12:23 Meze 2.5 m OFC 99.95% Copper Standard Cable Balanced 4 pin XLR versus Meze Mini XLR to 4.4 mm 1.3 m Balanced Silver Plated PCUHD Copper Premium Cable, magnitude and phase response. Those measurements are from a few weeks ago, covered in [2].
13:20 My current SPL calibration method. 14:35 covers my previous EQ profile prior to adopting binaural head-tracking with free-field EQ.
16:39 Tip for noise floor reduction. Mic input preamp gain adjustment for setting digital SPL level.
17:37 Lavricables Grand 1.2 m 4-core 20 AWG cryogenically treated 6N pure silver multistrand Litz with Lavricables "Carbon" terminations and Y splitter
19:08 Cable swapping considerations
20:12 HiFiMan HE1000se stock 3 m balanced cable measurement. Checklist.
22:42 First sine sweep measurement. 24:15 Right in-ear microphone nonlinearity.
24:39 Lavricables Grand measurement with the HE1000se. Videographic "proof" of the cable swap.
26:49 HE1000se stock balanced cable versus Lavricables Grand from 2 Hz to 96 kHz. 29:38 Lack of significant phase response differences
30:10 HiFiMan Arya Stealth stock 1.5 m unbalanced cable and Lavricables Grand measurements videographic "proof". I noticed after the fact that I should probably be gentler with my cable terminations...
31:56 The importance of volume-matching when A/Bing
33:26 Arya Stealth Lavricables Grand sine sweep. 34:22 Arya Stealth stock unbalanced cable versus balanced Lavricables Grand from 2 Hz to 96 kHz.
34:58 Arya Stealth Meze 1.2 m silver-plated upgrade cable swap and measurement
36:49 Arya Stealth Meze silver-plated upgrade cable versus Lavricables Grand
38:05 Close-up of ultrasonic responses
39:51 Meze Elite stock balanced cable measurement
40:44 Videographic "proof" of swapping to the Meze premium silver-plated cable
42:10 Meze Elite premium silver-plated cable measurement
43:20 Meze Elite stock balance cable versus balanced premium silver-plated cable.
45:09 Wrapped phase response and ultrasonic response comparison
45:49 Simulating "music" with multitone signals. Arya Stealth with balanced Meze silver-plated upgrade cable.
47:04 Multitone measurement for the Lavricables Grand
48:36 Multitone measurement comparison
50:54 Listening impressions
53:16 Bending sound to your will, the objective way. EQing down peaks.
54:50 Fine-tuned EQ.
55:51 Why EQ (when done right) does not degrade sound quality. Minimum-phase EQ can correct headphones' inherent phase distortions and hence transient response. https://diyaudioheaven.wordpress.com/... [4]
57:50 EQ itself does not introduce harmonic distortions. EQing advice in https://www.head-fi.org/threads/meze-... (post #4,665) [5].
59:51 In-ear speaker response and binaural head-tracking. See https://www.head-fi.org/threads/in-ea... (post #61) [6] .
1:03:42 Conclusion