Always low output impedance, high input impedance. A factor of eight or more. 100Ω output impedance on the DAC, there is probably more than 10kΩ input impedance on the Atom. The same thing goes for the headphone amplifier output. Low output impedance, preferably 1Ω or less, which means that it can drive headphones with as low impedance as 8Ω.
I see, i'll have to figure it out, for my self
The audio world is always more and more reveiling, great.. I'll make some research, my not perfect English comprehension is not of the best, so i'll have to engage.. For example I didn't get the 8ohm factor, no, actually i didn't get a lot of what you said, but i'll happy to figure it out in a n'era-future.. For example, I have headphones from more than, 2 years, but i never run in 10k ohm, never Heard of that, i'm only started to interest to buy 2 days ago some dac+amp separately, i'll always had some amp+dac combo, things ready for the go, like Sony Hw700ds, SoundBlasterX G6 and Sony Pha-3.. For now i just want to make sure the EL8 Closed+ JDS Labs ATOM+ Topping D50 works perfectly. I was also che king to spend around €200 on optical Cable + 200€ RCA cable, but someone says to not spend more than 25€ a cable, but i'm very temped to make a purchase that would work for the rest of my life pratically :/