Question about Soundcards (intern or extern)

I want to get new headphones (Audio Technica ATH-M50x) and want to get a Soundcard improve the sound further, for listening to Music and Movies and Gaming.

Now i dont know if i should get a Intern or Extern one.

Are there differences?

And i dont know which one i should get. I read a bit about it and found the Creative Sound Blaster Z and FiiO E10K Olympus 2 which some people sayd are good. they both fit in my budget. But well i dont know if they are good and wanted to ask for another opinion and would like to know if those Soundcards are compatible with the Audio Technica ATH-M50x or if there a problems.

My Motherboard is the MSI H170A Gaming Pro Intel H170 if that is important to know.

i hope someone can help me.

greetings