That I know of, 1 sound-card can't take 2 Sound Sources and split them into different Outputs. I'm pretty sure it requires two sound-cards (or 2 sound-devices such as a USB Headset), one to be labelled "Headphones" and one to be labelled "Speakers". Since Windows sees all output locations from Card 1 as a single output it routes all sound directed at that card through all outputs connected to it. So I
think to have sounds like you want you will either need a second sound-card or a USB Headset.
I could be completely wrong too, so maybe someone will confirm/deny that.
I know to run my sounds like you want I use an on-board sound-card ('Headphones") for the AH Vox and all Voice Comms I use, and the add-on sound-card ("Speakers") runs my 5.1 speakers for the Game sounds, Music, General use, etc.