HiFiMAN Arya: https://www.headphones.com/products/hifiman-arya?_pos=1&_sid=03e81c948&_ss=r
Written review and measurements: https://www.headphones.com/blogs/news/hifiman-arya-review-a-planar-hd800s
Forum thread: https://forum.headphones.com/t/hifiman-arya-official-thread/2577/66
Become an expert on headphones: https://www.headphones.com/pages/research
Learn about headphone measurements and frequency response: https://www.headphones.com/pages/measurements-and-frequency-response
How frequency response impacts sound signature: https://www.headphones.com/pages/how-frequency-response-impacts-sound-signature
Podcast: https://theheadphoneshow.fireside.fm/
Source equipment
Amp - SPL Phonitor X: https://www.headphones.com/products/spl-phonitor-x-headphone-amplifier?variant=376861360149
Amp - Cayin IHA-6: https://www.amazon.com/CAYIN-Balanced-Fidelity-Headphone-Amplifier/dp/B01LZK9UWK
DAC - iFi Pro iDSD: https://www.headphones.com/products/ifi-audio-pro-idsd-dac?variant=12694240985159
DAC - Mytek Liberty: https://www.headphones.com/products/mytek-digital-liberty-dac-headphone-amplifier?variant=17124771102791