It could be possible that the power output of the board is not sufficient, but most motherboards I've used have been more than suitable for 80ohm phones. I imagine it's the sound of the headphones to be honest.

The kz has more of a v shaped sound and you may just prefer the fun that having raised treble and bass gives.

An amp could help but it's more likely that other headphones would be better suited. See if there's any local audio/hifi stores, they should be happy to let you audition some gear.