Issues with DD 5.1 Audio

[Jasthrus]

Windows 7 32-bit Home Premium
Intel Core2Duo @ 2.8gHz (OC @ 3.4gHz)
ASUS P5Ql/EPU Motherboard
2GB Kingston Value Ram DDR2
Sapphire Radeon HD5750 1GB DDR5
VIA HD 7.1 Digital OnBoard Audio

VLC PLAYER VERSION 1.1.7

Using MKV, AVI, MP4 A/V files, some XVID/DIVX coded, some h.264 coded.

ISSUE: Any file containing AAC, AC3, or any other 5.1 digital audio track (6 channel) using SPDIF interface (over optical cable connected to external Home Theater Receiver), I am not getting any digital content. My receiver decodes simply as PCM 48000 audio. ANY of the above mentioned file containing a DTS audio track plays correctly, and my receiver decodes as DTS audio. DVD playback allows DD 5.1, as well as DTS audio, so unsure as to why only the files are not allowing 5.1 audio. I have tried any and all options I can using the VLC options, and I cannot seem to get these files to play correctly. I had been using another player, which does play these files allowing simple SPDIF passthrough, letting my receiver do the correct decoding. The other media player does use AC3Filter, which allowed me to set it to passthrough very easily. However that other media player cannot load DVD's for some reason, hence why I changed to VLC. I just want to use one program for all my video needs, so if there is a solution I have not found, please let me know!

[mmika]

I have some music in multichannel format, DTS mostly but couple of titles in AC3. None of those (.ac3) works correctly - there is occasional song that's playable but mostly it's noise. Multichannel DTS, on the other hand, works great.
Some other players (using external ac3 filter) played all ac3 content without a problem. But I don't want any other player.

Is there a way to fix VLC's internal ac3 filter?
Thanks in advance.