Typical burn-in time?
What is the typical burn-in time for these HD-558 headphones?
Burn in isn't real. In reality, it's your brain adjusting to the sounds the headphones make much like how your brain takes a few days to get used to new glasses or how beer tastes better the longer you drink it.
These are super relaxed in sound, they should sound good almost immediately I'd you like relaxed, warm sound. Worst case, a couple of days max.