Getting 5.1 sound over SPDIF from my games with AC3Filter

TL;DR: I want my TF2 to have 5.1 over SPDIF. Can't use analog, no money for new card. Suggestions?

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Hey everyone, I just bought me a Sony HT-SS360 system for my room and have been experimenting with getting 5.1 sources for it. Most of my movies I, uh... acquired (cough cough) already have dts streams embedded in them, which were easily passed over SPDIF to my reciever in glorious 5.1 thanks to AC3Filter. The general concept is that the stream is decoded, encoded into AC3 (AKA Dolby Digital) using AC3Filter, and then streamed over SPDIF to my reciever.

So I was thinking, why not apply this process to every sound that comes out of my computer, not just movies? Now at this point those who know what they're talking about are thinking, "Why doesn't this guy just buy a sound card with DTS Connect or DD Live?" ...Well, the answer is, I'm poor   I'm stuck with on-board audio whose analogue inputs/outputs are all broken but with SPDIF left miraculously intact. So I only have this option.

A lot of searching has led me to only one solution: http://forums.whirlpool.net.au/forum-replies-archive.cf...
This guy has done what I've been trying to do myself, but so far it's not going so well...

So here's my questions:
1. VAC doesn't have a Windows 7 x64 signed driver, so in order to use VAC I gotta start windows with that "Disable Driver Signature Enforcement" option checked... EVERY time I start my PC. And that bootloader that will select it for me? Buggy and unreliable. Is there any other alternative?

2. VAC costs money. Is there any free alternative that might do the same thing?

3. In Graphedit (check AC3Filter's site), "Virtual Cable 1" appears only in "WDM streaming devices" which I think the OP mistook for "VDM". If I try to add it, it gives me an "Invalid Class" error... so what am I doing wrong?

If you made it this far, I commend you for not getting too bored by my post