Connecting PC to 5.1 surround

[JonnyCam]

I prefer ac3filter cos ffdshow does everything potentially, whereas C3filter only concerns itself with sound. Safer in my opinion

Yeah, my feelings too. I have dvi to HDMI to my TV, nd couldn't get the stereo sound to go to the TV (through the DVI/HDMI audio in on the tv)
now I upsample everything to 5.1, when it's sampled at 48 and above, so my mp3s are left alone.

I find passthrough AC3 is softer than the upmixed from AC3filter, so have adjusted the gains too (especially the center channel)

[Satori]

I have 3 x 1/8" jacks coming out of the back of the card for the analog sound. The three end in 6 RCA connectors. Two are for the center/sub, two for L/R, and two for LS/RS. The center channel RCA connector is split. I gave the wrong link on my last post, I actually use this to split the center channel RCA:

http://www.newegg.com/Product/Product.aspx?Item=N82E16882339070

Then all 6 go into my receiver's 6 channel analog in. The split center channel goes into the left and right channels of the TV, so it is in essence a center channel speaker. My TV has a switch that sends the one input to both speakers; otherwise I would have to split it again. Some TVs have a “Mono” in that does the same thing.

When I want surround sound (for DVD movies for example) I mute the TV and watch using my 5.1 home audio setup (I have a dedicated center channel speaker as a part of it). I guess you could use the TV as the center channel speaker instead of the center channel speaker in the home audio setup, but then volume across all the speakers becomes an issue.

The key here is having 6 channel (or more) analog in on the receiver and a sound card that can expand 2 channel sound into 6 channel sound.

The sound card also has to do a good job of it. I tried this using the "Speaker Fill" option on my Realtek onboard sound, but it sounded like S**T. The X-Fi Xtremegamer I am using sounds a lot more realistic.

I found a web page that describes all the options and tradeoffs for you:
http://www.missingremote.com/index.php?option=com_content&task=view&id=3027&Itemid=1