Xonar DGX 5.1 and headphone options

So I just set up this card today and I'm liking it for my PC speakers; big improvement over the bluetooth speaker I was using before.

​

That said, after installing the drivers, it pretty much just auto takes priority? For headphones, I'd always use my USB Dac (Ibasso d4 mamba). Now, when I set that to default device, I get no sound from it and still only getting sound from the DGX card.

Is this normal? When I was using the bluetooth speaker, i could just change the default device and change from headphones to bluetooth w/o having moving plugs around.

​

Now for my other question. If I just say screw the USB dac all together and just stick w/ the DGX, do I lose sound quality by plugging my headphones into my PC speakers? Or would it be preferential to go to my card itself, unplug the speakers and plug in my headphones every time I want to change between the two?