Your headphones have 3 speakers in each cup so you get 5.1 audio. The media player should be setup to decode the audio (Dolby Digital and DTS) to multichannel pcm (5.1 speakers) then that is sent to the turtle beach sound card through USB. The turtle beach sound card will then convert that multichannel pcm to analog using a DAC (digital analog converter). From there it goes to the built-in headphone amplifier and then to your headphones. Now you get 5.1 sound through your headphones!
When you use your headphones, you are not using the digital output so any changes you make there won't make a difference. If you select the one labeled "Speakers" that will affect your headphones. The Digital Output is for the optical output which you are not using if you use headphones.
Your headphones have 3 speakers in each cup so you get 5.1 audio. The media player should be setup to decode the audio (Dolby Digital and DTS) to multichannel pcm (5.1 speakers) then that is sent to the turtle beach sound card through USB. The turtle beach sound card will then convert that multichannel pcm to analog using a DAC (digital analog converter). From there it goes to the built-in headphone amplifier and then to your headphones. Now you get 5.1 sound through your headphones!
When you use your headphones, you are not using the digital output so any changes you make there won't make a difference. If you select the one labeled "Speakers" that will affect your headphones. The Digital Output is for the optical output which you are not using if you use headphones.