Welcome back to the channel—I'm Colin, and this one is a straight-up op amp comparison using the Fosi Audio ZH3 DAC/headphone amp. I rolled eight dual op amps total: three IC chips (NE5532P, OPA1612A, and Muses02) and five discretes (Sparkos SS3602, Burson V7 Vivid, Burson V7 Classic, Muzg Audio JFET, and the Staccato OSH). I lined everything up with pin 1 facing the camera so you can see the real-world size/height differences, and I also called out approximate pricing—because yeah, perception and price bias are a thing. For the actual test, I installed each op amp in the ZH3 and recorded test tracks through line-out. Fosi confirmed to me that all three modes—line out, headphone out, and pre-out—pass through the swappable op amps, so the changes (if you hear them) should apply across outputs. I also let each op amp sit for 15 minutes before recording so everything hits operating temperature. The sound demo is a blind test labeled A to H across different genres, so you can pick what you like without knowing what it costs. One practical note: everything fits in the ZH3 except the Staccato, which needs extension leads and proper insulation to avoid shorts.