Key posts:

• Start of audio journey (Arya Stealth and Meze Elite): https://www.head-fi.org/threads/meze-audio-elite-the-new-isodynamic-hybrid-array-headphone-official-thread.959445/post-17509345 (post #4,541)
• Second summit-fi listening session: https://www.head-fi.org/threads/meze-audio-elite-the-new-isodynamic-hybrid-array-headphone-official-thread.959445/post-17548308 (post #4,660)
• Other audio journey summaries: https://www.reddit.com/r/headphones/comments/189dpt3/comment/kbs5o4q/?utm_source=share&utm_medium=web2x&context=3, https://www.head-fi.org/threads/anyone-into-crossfeed.961533/post-17958297 (post #43)
• EQing by ear; opinions on "soundstaging" and "imaging": https://www.head-fi.org/threads/meze-audio-elite-the-new-isodynamic-hybrid-array-headphone-official-thread.959445/post-17549413 (post #4,665)
• In-ear mics and EQ fine-tuning: https://www.head-fi.org/threads/meze-audio-elite-the-new-isodynamic-hybrid-array-headphone-official-thread.959445/post-17743502 (post #5,152; includes Sennheiser HE-1 measurement and impressions). See post #5,153 for my early headphone distortion measurements.
• In-ear cable measurements: https://www.head-fi.org/threads/in-ear-microphone-cable-measurements-for-planar-magnetic-headphones-frs-are-indeed-identical.970202/, https://www.head-fi.org/threads/continuation-of-mr-haelscheirs-excellent-thread-responding-to-wavetheorys-video-series-on-cables-mattering-for-audio.970430/ (post #8), and https://www.head-fi.org/threads/my-six-year-old-daughter-flawlessly-passed-a-blind-test-between-a-silver-plated-wire-and-a-copper-one.970695/page-23#post-17891886 (post #345)
• Stax SR-X9000 impressions: https://www.head-fi.org/threads/stax-sr-x9000.959852/page-178#post-17793964 (post #2,659), https://www.head-fi.org/threads/stax-sr-x9000.959852/page-179#post-17830373 (post #2,678)
• Earfish binaural head-tracking: https://www.head-fi.org/threads/anyone-into-crossfeed.961533/page-3#post-17950791 (post #32 and on), https://www.head-fi.org/threads/recording-impulse-responses-for-speaker-virtualization.890719/page-120#post-17951999 (post #1,789 and on) https://www.head-fi.org/threads/in-ear-microphone-cable-measurements-for-planar-magnetic-headphones-frs-are-indeed-identical.970202/page-5#post-17801518 (post #61), https://www.reddit.com/r/headphones/comments/189dpt3/comment/kbs5pic/?utm_source=share&utm_medium=web2x&context=3
• HRTF considerations: https://www.audiosciencereview.com/forum/index.php?threads/hifiman-susvara-headphone-review.50705/page-57#post-1853760 (post #1,137)
• On binaural decoders and threshold EQ compensation for blocked canal ear gain discrepancies: https://www.head-fi.org/threads/recording-impulse-responses-for-speaker-virtualization.890719/page-121#post-18027627 (post #1,812)
• HE1000se measurements (and Meze Elite exceptionality), diminishing returns / "technicalities" skepticism, and QC issues: https://www.head-fi.org/threads/hifiman-he1000-se.886228/page-320 and page-321 etc., https://www.head-fi.org/threads/totl-disappointments.925164/page-63#post-17949397 (post #936)
• On driver burn-in: https://www.head-fi.org/threads/hifiman-he1000-se.886228/post-18012543 (post #5,049)
• Arya Stealth and HE1000se pad rolling: https://www.head-fi.org/threads/earpads-for-the-hifiman-arya-now-available.961609/post-17961697 (post #84)
• EQing headphones to an identical frequency response: https://www.audiosciencereview.com/forum/index.php?threads/hifiman-susvara-headphone-review.50705/page-57#post-1853760 (post #1,137)
• "Measurebating" (exceptional Meze Elite multi-tone distortion performance): https://www.head-fi.org/threads/recording-impulse-responses-for-speaker-virtualization.890719/post-17955514 (post #1,801), https://www.audiosciencereview.com/forum/index.php?threads/hifiman-susvara-headphone-review.50705/post-1888972 (post #1,183)
• FiiO K9 Pro ESS defense and DAC and amp A/Bing experience: https://www.head-fi.org/threads/fiio-k9-pro-hi-fi-deskdop-dac-bluetooth-amplifier%EF%BC%8Cxlr-rca-4-4-optical-coaxial-interface.952664/page-148#post-18078740 (post #2,211 and on), https://www.head-fi.org/threads/recommend-a-high-end-dac-and-amp-stack-to-a-genuinely-curious-objectivist.972411/#post-18078699 (post #9)
• "A case for multi-tone and higher-order testing of headphone distortion" and latest measurement methodology: https://audiosciencereview.com/forum/index.php?threads/master-complaint-thread-about-headphone-measurements.18451/page-61#post-1956895 (post #1,210)

YouTube, Idagio etc. (PC audio) [-> VB-Cable (24-bit 48 kHz) -> [(foobar2000 -> foo_record -> bs2b crossfeed or other DSP | Reaper -> SPARTA AmbiRoomSim (stereo distance simulation; reflections disabled) -> SPARTA CroPaC ambisonic to binaural decoder with Earfish HRTF and head-tracking)] -> Equalizer APO with fine-tuned PEQ -> FiiO K9 Pro ESS -> internal ES9038PRO DAC -> (internal THX 788+ 2.1 W amp -> Youkamoo 1' male 4-pin XLR to dual male 3-pin XLR adapter -> Monoprice Premier 1.5' XLR cables | more powerful solid-state amp if needed) -> [Nobsound Douk Audio ONE Little Bear 3-IN-1-OUT switchbox] -> WJSTN 6" XLR cables -> matching 1-IN-3-OUT switchbox -> eBay microdot2009 dual female 3-pin XLR to female 4.4 mm adapters -> (Meze Audio silver-plated upgrade cable -> HiFiMan Arya Stealth | Meze Audio silver-plated PCUHD premium cable -> Meze Elite Tungsten with hybrid pads | Lavricables Grand -> HiFiMan HE1000se with custom pads)

See https://www.head-fi.org/members/mrhaelscheir.572134/#about for an index of my key posts.