Goal: 5.1 sound output from digital optical/coaxial audio input please.

Problem: 990 recognizes/defaults to PCM output when multitrack media files are played. This occurs regardless of whether MP3 music is played via WinAmp 5.1 Surround Edtn or avi movies played via ZoomPlayerWMV Pro 4.5. This leads me to believe that it is not a codec issue. I have not rented/played a digital multitrack DVD yet. (If I listen to FM radio then all surround mode options are available and output is 5.1 sound)

Misc Info: I just traded-in/upgraded from a 1070 receiver to the 990/7125 combo. Had great 5.1 sound output (via digital coaxial or optical connection) with the 1070, or 1070 pre-outs to the 7125. I believe that the 990/7125 also briefly output 5.1 sound until I changed a setting somewhere? I have since used the 'RESET' option and still the 990 recognizes/defaults immediately to PCM and 2 channel output.

Setup: Outlaw 990/7125, speakers 5.1, PC with Creative SB Audigy2 ZS Platinum, optical TOS link cable.

Configuration: Soundcard configured for digital output to the OPT1 input of 990. Internal crossover of the powered subwoofer is turned off. No video input to the 990 (...since both the PC's graphics card and LCD moitor will natively display 1920P X 1080P). 990 configured as follows

Main Menu
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-Input Config/Go To Audio Inputs/AUX/ ...from here I only have bypass, upsample or PCM 96/24 ST as the available choices. More choices are available BEFORE I try to play any media file, but immediately upon playing media or afterwards, ONLY these choices show up. Initially I choose PLII Movie or PLII Music. The same thing happens if I try to configure the OPT1 input to one of the video input config settings and play a media file.

-Speaker Size/ Front L/R, Center, Surr L/R all set to Large. Subwoofer: L/R+Sub.

-Speaker X-Over/ Front L/R, Center, Surr L/R all set to 60Hz.

-Surround Config/ ...factory default settings.

-Channel Calibration/ ...factory default settings. (0db).

-Delay Adjust/ Front L/R 10Ft, Center and Sub 8Ft, Surround L/R 5 Ft.

-System Config/ OSD Time Out: On, Display Time Out: On, Volume Default: Default, Default Vol Set: -25db, all other settings are factory defaults.

-Multi-Room Config/ ...factory default settings (Off).

ANY and ALL ideas, suggestions, questions or deserved ridicule gladly accepted. Thankyou for your time.