I bought a usb headset(Arctis pro no dac) and a sound card. I didn't realize that the sound card would be useless with a usb headset. The headset does however come with a 3.5 mm adapter. so i'm wondering then if i use the adapter and plug it into my sound card, will the headset then use the sound card? If so will i loose any of the sound quality. I want to know before i open the sound card.
You don't need a sound card, just connect the USB to the computer. If you want to see if there is any quality difference with the adapters, just plug them into your computer without the sound card and see how they work.