Creative Sound Blaster Z SE vs Fiio K3 for desktop headphones?

Hi guys just wondering if there is any point going back to a dedicated sound card or not? I've just changed my loop so that my graphics card is horizontal again and that has opened me up to being able to use my PCIe slots.

Right now I'm running an optical from my B550 Unify X motherboard to Kanto YU6 for desktop speakers and using a Fiio K3 for desktop headphone use.

My understanding is if running optical to my Kanto to allow them to use their own dac/amp it doesn't really matter if I use a sound card or mobo.

Headphones though it would be about a USB DAC/amp or plugging into a soundcard. Only using some Philips X2HR just now which the Fiio can power fine, but I'm considering grabbing some 660s.

Apparently the sound card can do up to 600 ohms.

Cheers.