I think it likely that the switch on the 990 is designed to pass the original DVI bandwidth and maybe a little more since it has been capably doing so for many for a long time. However it should be simple to test the theory by removing the 990 from the pathway and just running high speed HDMI cable. If it allows 3D, game over. Bypass the DVI and use the analog through the 990. Will get much easier (we hope)when the 978 makes its appearance.
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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