S/PDIF, PCM, AC3, DTS, Sage TV, Yamaha Receiver

[OldPCGUY]

I built my own HTPC and have been using Sage TV for a few months now. For the issue I am having I have to describe my hardware and software.

Yamaha 555 HTR with S/PDIF Coax input(5 years Old) with 6 Speakers
ASUS M2N-E Motherboard with S/PDIF Coax Output
Sage TV
AC3 Filter Settings Software
Pioneer Upconverting DVD Player with S/PDIF Coax Output for comparison (6 months old)

What I am observing is that for a DVD with DTS 5.1 Enabled I get different sound when comparing my DVD player to my PC.

I have observed the following:
1. When Pioneer DVD plays my Yamaha Display Indicates it is recieving a DTS signal and automatically implements DTS DGTL 5.1 sound. It sounds great.

2. When the PC plays the same DVD my revciever says it is getting PCM and the receiver Indicates Dolby Prologic II. It sounds good but not as good as DTS.
My Yamaha Manual states the subwoofer output is disabled when the input signal is not DTS.

3. I accesed the AC3 Filter Settings and have properly set:
SPDIF passthrough checkboxes for AC3, DTS and MPEG Audio.
SPDIF/DTS Mode - Auto
SPDIF/DTS Conversion - Do not convert

4. Sage TV is configured:
Audio Render - Default DirectSound
MPEG Audio Decoder Filter - AC3filter

5. My ASUS M2N-E board has a SPDIF output which should support DTS pass through

So I am a little confused with a few terms here. Here are a few statements and questions.

A) SPDIF is a standard that allows for DTS, and older PCM audio streams to be transmitted.
B) Does PCM imply that a DTS source is not being transmitted?
C) Is my receiver just to old to receive PCM DTS?
D) Does PCM imply only 2 channel audio?
E) Do I need to buy an Audio Card with DTS passthrough capability on its SPDIF output?


Any help would be greatly appreciated

[planetc]

I might be wrong, but I seem to remember a setting in ac3filter to disable pcm output/passthrough, I know I had to play around a bit trying different combinations before I got dts to passthrough properly and I think this was one of the key things.

[wylee]

Your soundcard should also be set for passthrough as well - some drivers may be doing additional processing so you're not actually getting a passthrough signal although AC3Filter is set to do so.

I had to set AC3Filter to passthrough, then my c-media driver had to set at the same time to get DTS and AC3 signals to get to my receiver properly.