How do you have your STB hooked to your 990? I have a Mototola 1216 box for my u-verse. I have it hooked into my pre amp with an hdmi cable. It works great BUT I found out that the software in my box will only output 2 channel PCM through the hdmi at the present time. The preamp defaults to pro logic II for that, which actually does a very nice job of it. If I would use a digital audio hookup , either toslink or coax for the sound, the Dolby Digital would come though fine.
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Main system:
Integra dhc 9.9
Threshold SA/4e pure class A
Emotiva XPA-1 (2), XPA-5
(2) Threshold S200's
Thiel 3.6 main speakers
(2)Velodyne F1500r subs
Polk RTI28 surrounds
B&W HTM center
OPPO BDP-83 universal player
Samsung HLT6187 led DLP