Multichannel Sound, Wav, and which sound card

Has anyone used multichannel wavs in v4?
I have to play one for a project, its a 6 channel surround mix, file stream doesn’t show a duration, wave player sees it as 6 channel but plays back hiss, I converted it from 24bit to 16bit and still no joy.
I have got ac3 working out of a shitty external sound card, but it sounds shitty :)
Has anyone tried this successfully?
Can you recommend a sound card that will cope with a ac3 or multichannel wav, preferably embedded in a avi, as I will have to sync them otherwise!
Thanks for your input!
in case it helps the wav is

esi 64se works