I tested my 990 today with multiple recorded shows. If I set the TiVo to PCM, everything is output as PCM, even the shows broadcast in Dolby Digital.
The 990 has no problem locking on to these two- channel signals and applying Dolby processing to them.
I selected "Planet Earth" for my DD test as it is broadcast in Dolby Digital 5.1 and has some really stunning surround effects. I left the 990 set to PL-IIx-Movie and played the same sequences with the TiVo alternately set to Dolby Digital and PCM mode.
When I set the Tivo to output in PCM, surround detail was greatly diminished. Most of the localized, individual sounds that were distinct and directional in Dolby Digital were lost in the general soundfield.
Shows broadcast in PCM (or DD 2.0) showed no difference in quality or surround effects with the Tivo set to DD or PCM. This is as I expected as the 990 is applying processing to the same two channel signal.
While the 990 had no problem outputting sound for ANY recording while the TiVo was set to PCM, this is not a solution for me. A large percentage of my recordings are of shows with DD 5.1 soundtracks and I definitely prefer to hear those soundtracks when they are being decoded directly by the 990.
As I said, I don't think this is an issue with the TiVo as I was not able to duplicate the problem with a 970 or a Denon Surround receiver.
TP
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Outlaw 976, Outlaw 7700, Pro-Ject Phono Box S
Sonus Faber Domus Grand Piano (F&C), Niles HDFX (Surr. & Rear Surr.), Outlaw LFM-1 Plus, Velodyne SMS-1
Sonos multi room audio
Video: Sony KDL-46V2500, OPPO BDP-103, TiVo Premiere XL4
2-channel: Outlaw RR2150, SF Concerto Home, Outlaw LFM-2