question about headphone dac/amps

[moon man]

As title , how do you use a digital to analouge converter(i.e in a combined amp dac ): isnt the line out signal or the headphone signal already converted to analogue with the players own dac
sorry if its a dumb question

 

[moon man]

thanks for the replies it was looking at this www.ibasso.com/en/products/show.asp?ID=32 that promted me to ask