Asus Xonar DX or DG with headphone amp ?

So as I have been posting lately I got new headphones on the way and I needed a soundcard for them, but it was brought to my attention that the Xonar DX might not be the best choice because it doesn't have a built in headphone amp like the DG does. I got my DX and have ordered a DG and whichever is better I will return the other for a refund. I have also ordered a FiiO E11 portable headphone amp.

So simple question should I keep the DX and the FiiO E11 will be enough or will I return the DX and wait for my DG to arrive? I will be using the FiiO E11 regardless but I'm wondering if the extra price on the DX is worth keeping it for or is the DG practically the same with a built in amp?

The cards have completely different chipsets. I believe the DG is actually superior if you're only using it with Headphones, while the DX is a better option if you're going surround sound with external speakers. Namelessplayer will know better than I do, though, when it comes to sound cards. He's the resident expert in that arena. Happy gaming, BozBozanimal