I currently have 3 displays (dual monitors at 1080 and a TV in another room at 720) My current video card (5450) only outputs to two of them at a time, so when I want to output video to the TV I have to change my display and audio output settings.
I'm looking to add another video card so I can avoid having to switch the display settings, and as I understand it, I cannot output my audio through both my speakers and HDMI out at the same time.
Will I be able to output the audio over both HDMI outputs (on per video card) at the same time?
No you will not be able to as far as I am aware. Sound controller is embedded into the video card, and you can only have one default audio device selected, so it would either be sound though video card A or B not both.
Open Sound panel
Select Speakers as the default playback device
Go to the "Recording" tab
Right click and enable "Show Disabled Devices"
A recording device called "Wave Out Mix", "Mono Mix" or "Stereo Mix" (this was my case) should appear
Right click on the new device and click "Enable"
Right click on the new device and click "Set as Default Device"
Double click on the new device to open the Properties window
Go to the "Listen" tab
Click on the "Listen to this device" checkbox
Select your HDMI device from the "Playback through this device" list