I don't understand this. Going by this thread https://www.head-fi.org/threads/amplifier-specifications-am-i-getting-it-right.803665/ 20mw is good enough for 600 ohm cans and in the example given the amount of of mw needed for 93 db is higher than those of hd 600s. So why, given that 20 mw is enough for 600 ohm cans at normal listening volumes, 80 would not be enough for 600s?Right, it says 150mW @ 32 ohms and 40mW @ 600 ohms. Amps are often not linear but it looks like best case 80mW at 300 ohms and probably less, and will not have enough voltage to make the 600s sing like they should.
The Corda Jazz-ff swings 15V which is a safe number for working well with the HD 600 series.
I'm not trying to be a contrarian, I simply don't know much about it and am confused by all the conflicting information I find on the internet.