Here is a long shot - Make sure your video HDMI input matches the audio HDMI input. For instance if your cable box is on video HDMI1 then the audio has to be HDMI1 also. Any chance the HDMI cable is bad. Sounds like you have already covered the old "switched in headphone mode" and the venerable "its on mute" possibilities. Do any other HDMI inputs have the issue or are they all acting the same? Call Scott at Outlaw or maybe he will see this and PM you.
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Music system
Model 990/7500/Magnepan 1.6 QRs/Technics SL1200 MK2/Aperion S-12 Subwoofer/OWA3/Sony NS75H DVD
APC H15 Power Conditioner

TV System
Large Advent Loudspeakers/ Polk center/Monoprice surrounds/Panasonic Viera 42 inch/Onkyo HT-RC260/Sony BDP S590/Directv


Home Theater System
Onkyo PR-SC886/Outlaw 7125 Klipsch RF-82 L/R,RC-62 center, RB-35 SR/SL, BENQ HT1075, Outlaw LFM1-EX/OPPO BDP-83/Directv
Harmony ONE
Blue Jeans and Monoprice interconnects
APC H15 Power Conditioner