Mine sounded pretty crappy for the first 40 hours. The first hour really had me, seriously questioning the amp. After about 10 hours I could hear serious progress. Then at around 80 hours it really opened up and I stopped taking notes. I don't think that was just the caps, but rather the entire circuit was new. IMHO, everything breaks in because... well.. that's what my ears tell me. My best guess on that point would be the new lattice structure of the "solid" conductors adapt to current flow - like a river bed. I could be completely out to lunch on that point and I'm only parroting what others have said to me. So take it with a grain of salt.