I have a video card with HDMI out, and the audio works great. I also just got a sound card hooked up and it shows as a device in "Playback Devices" option of windows volume. I also have a bluetooth dongle that supports up to 7 devices, and two pairs of bluetooth headsets, one already synced, other new in box. How can I get the audio coming out of my stereo through HDMI, and my bluetooth headphones, or two pairs of bluetooth headphones when watching movies with my father?

HDMI to tv. Then audio out from tv to your stereo system. Do the headphones work along with the hdmi already at the same time ?

They aren't already working together. HDMI from video card goes to 720p Emerson TV. Optical out on that goes to Phillips FR-965. Headphones run off Rocketfish bluetooth dongle...

When you have the HDMI cable plugged in do you have sound on your computer or does it cut off?

? The sound comes out fine through the TV. Or through the stereo if I want it to as well. I want to also play the same sound (watching a movie, listening to music, etc) on two devices. I kept reading an extra sound card would be needed though it's seeming more like I just need a good sound card that is capable of doing dual out on it's own...

Most modern computers allow you to have sound at more then one source. That is why I asked if the computer had sound at the same time as your hdmi. If your hdmi has audio passing through it then your other channels are free to go where they can go.

Does the tv have audio out ports on it? If so and your passing audio through your hdmi cable then to listen to audio through the stereo while watching a movie it needs to be connected from the tv to the stereo (amp system).

Then with your bluetooth connected your computer should be free to use that as an audio connection for your headphones.

I do have HDMI out from video card going to TV. TV optical out to amp system. Plays through speakers but having trouble figuring out how to send it also to a device which is not default playback device in windows 8.1. I was reading this could be solved by having a separate audio card. Just purchased a basic one, but can't figure how to use one to out through HDMI (to TV to amp) and the same audio to my bluetooth headphones. Thank you for your time.

On your computer do you happen to know the driver for your audio? One popular one is named "Realtek". It is through that driver where you can change the settings to allow your headphones to work over bluetooth and also audio out through HDMI.

What computer system are you working with ?

Dell Inspiron 531s. 4Gb Ram. 500 Gb Seagate HDD. AMD Athlon X2 (64 bit) 2.1 Ghz Dual Core. Radeon HD 6570 1Gb GPU. Sound Blaster 5.1 Digital audio card (tried 3rd party driver, not sure if worked correctly) I've tried Realtek drivers in the past with similar installations and yielded some quality/signal loss, but otherwise liked the options of the driver at the time. I may try it again and see how it does for me.