Headphones

Yes it works fine.

Ifi go bar will power them better if your looking for a dongle but nah, those headphones need more juice…

I wouldn't recommend the Cobalt if you don't have anything yet. If you already have the Cobalt, try it and don't worry about it if it works for you.

Cobalt has very low noise but relatively high distortion. But the emphasis is on "relative." Most of us don't hear the levels of distortion that the Cobalt generates at normal listening levels. It's still way less than 2% THD, and still way less distortion than some pricey tube setups. You may even prefer that distortion. So again, listen to it loud and decide for yourself if it sounds good.

The other issue is that the Cobalt provides about 14mW of clean-ish power. That's enough to drive the 800S to a standard 110dB target. But those cans have rolled off lower bass. If you want to use EQ to juice the bass, you might run out of power. Same if you listen to quiet recordings without software gain adjustment.

Just sold Cobalt that came with used HD800S I bought, it make sound but very low volume. I am assuming it doesn't have enough power, get Qudelix 5k instead. It has been my go to for around the house listening with HD800S and LCD-4.