I do what Gonk does....as I have only the Oppo player for DVD's, CD's and DVD-A. I'm using the Oppo's digital output and when I select DVD on the 990, it defaults to Dolby Digital blah blah. When I select CD on the 990, it defaults to upsample, as that's what I told the 990 to default the CD input to.
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990
Adcom 7607
Oppo
Rocket RS 850's, 550's, Polk LS 90's
SVS PB-12 Ultra