PS3 - AC3 Audio Streams in Stereo

First, thanks for the fun piece of software. It's pretty amazing.
Sorry if this is a dunce question, but I've tried to find my answer via various Google & forum searches to no avail.
I can't figure out why my DVD rip with MPEG2 video and AC3 audio wrapped in an MKV is streaming fine to my PS3, but only in stereo - i.e. no 5.1 Surround Sound. There is only one audio track in the MKV as follows:
My Rendering Profile is set to Playstation 3. I do have an H264 BluRay rip with the same type of AC3 audio (though at a higher bitrate) that streams great with 5.1, so my guess is that the Profile.xml is doing something based on the video type? I'm not a programmer, so trying to parse what the Profile.xml is doing is kind of like reading a foreign language...
Any help is much appreciated. Feel free to point me to another thread if this has been discussed to death somewhere that I couldn't find.
Sorry if this is a dunce question, but I've tried to find my answer via various Google & forum searches to no avail.
I can't figure out why my DVD rip with MPEG2 video and AC3 audio wrapped in an MKV is streaming fine to my PS3, but only in stereo - i.e. no 5.1 Surround Sound. There is only one audio track in the MKV as follows:
- Code:
General
Unique ID : 176451987582924010351171111030130009725 (0x84BF6AAA718250E8BB3C6A8BC868E67D)
Complete name : H:\Media\Video\Movies\Groundhog Day.mkv
Format : Matroska
Format version : Version 4 / Version 2
File size : 5.11 GiB
Duration : 1h 41mn
Overall bit rate mode : Variable
Overall bit rate : 7 244 Kbps
Encoded date : UTC 2014-02-24 01:57:58
Writing application : mkvmerge v6.7.0 ('Back to the Ground') 32bit built on Jan 8 2014 15:03:17
Writing library : libebml v1.3.0 + libmatroska v1.4.1
Video
ID : 1
Format : MPEG Video
Format version : Version 2
Format profile : Main@Main
Format settings, BVOP : No
Format settings, Matrix : Custom
Codec ID : V_MPEG2
Codec ID/Info : MPEG 1 or 2 Video
Duration : 1h 41mn
Bit rate mode : Variable
Bit rate : 6 652 Kbps
Maximum bit rate : 9 800 Kbps
Width : 720 pixels
Height : 480 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 29.970 fps
Standard : NTSC
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Interlaced
Scan order : Top Field First
Compression mode : Lossy
Bits/(Pixel*Frame) : 0.642
Time code of first frame : 00:00:00:00
Time code source : Group of pictures header
Stream size : 4.70 GiB (92%)
Default : Yes
Forced : No
Audio
ID : 2
Format : AC-3
Format/Info : Audio Coding 3
Mode extension : CM (complete main)
Format settings, Endianness : Big
Codec ID : A_AC3
Duration : 1h 41mn
Bit rate mode : Constant
Bit rate : 448 Kbps
Channel(s) : 6 channels
Channel positions : Front: L C R, Side: L R, LFE
Sampling rate : 48.0 KHz
Bit depth : 16 bits
Compression mode : Lossy
Stream size : 324 MiB (6%)
Default : Yes
Forced : No
My Rendering Profile is set to Playstation 3. I do have an H264 BluRay rip with the same type of AC3 audio (though at a higher bitrate) that streams great with 5.1, so my guess is that the Profile.xml is doing something based on the video type? I'm not a programmer, so trying to parse what the Profile.xml is doing is kind of like reading a foreign language...

Any help is much appreciated. Feel free to point me to another thread if this has been discussed to death somewhere that I couldn't find.