Headphone collection: Sennheiser HD600/HD485/HD437/HD420/HD205/PC350/Unipolar 2000 (Without energizer). Sony DR-11/DR-5A/MDR-IF210 (Without infrared thingy). Fresh 'n Rebel Clam/Clam ANC. Philips SBC HP1000. Audio-Technica ATH-M30 (Not to be confused with the Audio-Technica ATH-M30x). Pioneer SE-450. Koss KSC75. Samson SR850. Tandy PRO-22. Alecto HT-39. Power Makes Sense "Stereo Headphone And Earphone Set" circa 1996. "STN-16", aka some BEATS ripoff.
DAC/AMP: FiiO E10K Olympus 2. Pepper Jobs C2PDA. My PC & Phone I guess
Music services: Tidal, Spotify (I have a headphone testing playlist at @Mynameisgregor)