Topping D50s vs Aune X8

Hello there, new to the forum here and i need your help.
I’ve got a pair of 660s and a pair of ATH-M40x. I just bought a topping A50s and i’m using my old Fostex HP-A3 as a dac but i wanna upgrade that as well. Which is the better choice between the two i mentioned in the title?

Thank you