trying to get all audio sources to go to all of 5.1 speakers

i seem to have had this problem a lot in the past, and every time i encounter it it feels different. for a while i could have sworn that i had things fine and set up, but i can only get some sources now to work for 5.1.
in the typical sense of playing a move/dvd in something like vlc media player, i guess if its available i can select 5.1 as the audi device and all works well. but in the past i have been able to get things to use all 6 speakers even when it was stereo sound. i suppose i am now at a loss that i have lost that, or wasnt too keen to it in the first place.
i curently am running windows 7 ultimate, and have a ht omega claro+ sound card. that is set up fine along with windows, as far as i can see at least. that device is selected and set up in windows and has been tested for all speakers. however i dont know if there is any option that i am missing that might allow that filtration of sound into the six speakers that i have somehow managed in the past.
i think the last program i used was from realteck before i got the new soundcard and it had a speaker fill option or something of that sort. i may try to get back in contact with the ht omega people again to see if it anything i can do on their end. but when i was originaly looking in a vlc forum to find something i saw someone saying that usualy windows will do everything itself so long as you are set to 5.1 sound and it should come out all speakers.
the last thing i can think of to mention is that i have gotten some codex packs from here in the past, and am also not sure if any of those could be incorectly/only partialy functional and causing some of this. if they might, i would also question a safe way to uninstal or even reinstal if i should need them.

thank you for all help.