Good, now start something playing .... something long lasting ......... and while it is playing, go to the output tab of PulseAudio Volume Control ...... and there change some settings.
There should be a horizontal volume control slider and a similar box to those on the Config Tab, from which you can choose which card should get the output ...... while the audio is still playing these will show, else they will not.
You should bring the volume up so the variation is about half way and choose one card and then the other.
The correct card should give the sound to the speakers.
Please report that
1. you are seeing the volume indicator on the playback slider vary with the audio you are playing
2. whether or not you are hearing the sound from the speakers on one of the cards.
If you see the volume level varying, and hear no sound from the speakers, then you should check that the speakers are connected to the correct socket on the sound card.
If in doubt try a couple of them with the sound playing .....