Sorry I did not see this sooner, been busy most of the evening.
The Amp card just uses the inbox MS UAA audio drivers. No need to load any special drivers for it.
First, check to make sure you have the 4 pin molex plugged into the amp card. Also make sure that you have firmly plugged in the speaker block to the amp card and that you have good connections and no shorts on the speaker wires.
Assuming all that is good which looks to be the case from the write up, the likely issue is you have not selected the D2 Audio codec as the default playback device.
Right click on the speaker icon in the system tray and select payback devices. You may need to try a couple of the different playback devices and set them as default playback.
You will probably see 3 or 4 different codecs installed (HDMI, SPDIF, and 2 sets of speaker outputs). One speaker output is the realtek, the other is the D2Audio codec. I am guessing you probably have the realtek codec as the playback device and you need the amp card set as default.
As mentioned, there are probably 2 different sets of speaker outputs listed with one being the realtek, the other is the amp card (though it is not deliniated as amp).
Set this as your default playback device. Then go to configure device and set up the speakers based upon how many you have (5 + sub) and test speaker outputs. If you are hearing sounds, then go to the properities window and select enhancements. Set Bass Enhancement, Speaker Fill, and Loudness Equalization. Then go to the advanced tab and set your default format. Any of the studio quality settings should be fine.
This should get you going. If you have done all that and it still does not work, post here and I will see what else I can think of, but I expect this should take care of it.