How best to interface an old analog receiver with an optical source?

[Qaureus]

I have an old Pioneer VSA-805S amplifier which I wish to use with an optical audio source.

Firstly, I am a little confused as to exactly what the VSA-805S is! I believe it is technically an AV Receiver (as it can pass through composite video)? However it only has analog inputs (RCA connections) and it only has stereo audio inputs. But it does have outputs for surround speakers. How can this box provide surround sound if it doesn't have any digital or analog surround inputs? Does it just output the same stereo signal through the rear channels? In which case I guess it wouldn't be able to use any 5.1 audio tracks?

I think therefore I simply need a 2.1 DAC that will take the optical input and provide a stereo output. Then I can plug in front left and right speakers (and maybe a center) and then probably not bother with rear channels for TV etc (the only benefit might be for music?).

Sorry for the myriad of confused questions! Many thanks for your help!

 

[americanaudiophile]

Older surround sound receivers used processing such as Dolby Prologic to derive surround sound from 2 channels which had center and rear channel information encoded in the stereo signal. Had it's limitations but that was where the tech was at. No digital audio anyway at that time.
All you need is a DAC like this one
http/www.parts-express.com/parts-express-dac-digital-to-analog-converter-(51-compatible)--180-999
The DAC doesn't provide a .1 bass channel and there is no place to connect it to the receiver if it did. The receiver will remove the bass from the 2 channels and send it to the subwoofer. It will also extract the center and rear channels and send them to the speakers.
The rear and center channel is more useful on movies than music for most people. Center channel is for dialogue, rears for special effects. The receiver will have different surround modes for movies and music.
It is important to set the receiver up correctly. I hope you have the owners manual since it doesn't seem to show up in a quick search online.

 

[jdlech]

Confirmed, your receiver uses Dolby Prologic, which is encoded directly into the 2 channels. Additionally, your receiver has a "simulated surround" mode - meaning it can attempt to create surround sound from sources that have no surround sound encoded. Hope you got the remote with your unit, as most of the controls are remote only.