Bigkidz,
He's not asking about a digital cable (input cable to your DAC). He's asking if he will hear a difference after "upgrading" from a receiver (that accepts digital optical input) to an older higher quality 2-channel analog seperates rig that does not have any digital inputs (no optical, no coax). He wants to connect his TV source using RCA analog connections to the pre-amp.
Ramax,
I did a bit of research to refresh my memory. The 3 Adcom components you list, when added together, basically get you the functionality of an old pro-logic receiver. All combined, they provide Dolby pro-logic processing of an analog signal, 5 channels of amplification, etc.
So, if your goal is to have decent Dolby pro-logic for TV, plus all the other features of an old pro-logic receiver, go for it. However, if it were me, I would pass. This technology has been replaced long ago by better stuff. I would highly recommend that you spend a bit more money on a good current HT receiver. If you insist on the old obsolete Adcom stuff, you might want to consider purchasing the Adcom GDD-1 to add Dolby Digital to the stack of components. However, you would then have a total of 4 components doing the same work as an old, first generation Dolby Digital receiver, and you would have 4 boxes, plus all of the required cabling, added electrical requirements, etc.
Get a new receiver (or even an older 5.1 channel DD receiver). BTW, the new receivers have lots of great features that are worth the money. Specificically, some of the new surround formats are very good, plus auto-calibration/equalization is built into many of them.
TIC
