I think you need to look a little further. Some of this depends on whether you have a AVP or an AVP2.
S/PDIF or optical can carry 5.1 Dolby Pro Logic and DTS formats, although not the new lossless formats introduce with Blu Ray (DD HD or DTS-MA). S/PDIF can only carry 2 channels of LCPM. But, Blu Rays have to have the original lossy formats on them, as well as the new lossless formats.
From what I can tell from reading, the AVP supports the original Dolby Pro Logic format , but the AVP2 added Dolby Pro Logic II (PLII). Original Dolby Pro Logic was 5.1 channel, but it tended to collapse sound into the center channel. Dolby Pro Logic II (PLII) is more natural. PLII was introduced by Dolby in 2000, so it was not in the AVP but was in the AVP2, which came out about 2002.
Since the AVP and the AVP2 AVP2 can decode both Dolby Pro Logic and DTS, although not the new lossless formats (DTS-MA and Dolby HD), if the PS/3 can put out Dolby Pro Logic or DTS (lossy) and you can get it to a S/PDIF cable, then the AVP should be able to decode them as 5.1 signals. On a Blu Ray player, there is an option to but out the lossy (D PLII or plain DTS). DVDs come with the lossy format only.
The AVP2 Manual describes using Pro Logic II, both movie and music modes. The AVP manual is also on the Proceed website.
The AVP2 also added LCPM support, including 24 bit 96 KHz digital signals, by a solftware upgrade. See the review here I cannot tell if the AVP does 2 channel LCPM over S/PDIF or not. It does have AES support from a CD transport, but that is not what you are looking for.
The new lossless formats DTS- MA or Dolby Digital HD can also be converted to LCPM or can converted to analog. As part of the conversion, a multi-channel signal can be converted to stereo. I do not know what the PS/3 does, but most Blu Ray Players, for example, can convert 5.1 DTS-MA to either 5.1 or 2 channel LCPM or 5.1 or 2 channel analog.
The AVP probably has a better DAC than the PS/3, so if you can send a 2 channel LCPM S/PDIF to the AVP2 you can use the DAC in the AVP.
There is lots of detail here. But don't give up on a 5.1 digital signal. It should be possible. Hope I got most of this right. Good luck.
Disclaimer : I have never worked with either the AVP or the AVP2 or the PS/3. But, from what I read, getting a 5.1 digital signal from the PS/3 to the AVP or AVP2 should be possible. And certainly a 2 channel analog should be possible.
S/PDIF or optical can carry 5.1 Dolby Pro Logic and DTS formats, although not the new lossless formats introduce with Blu Ray (DD HD or DTS-MA). S/PDIF can only carry 2 channels of LCPM. But, Blu Rays have to have the original lossy formats on them, as well as the new lossless formats.
From what I can tell from reading, the AVP supports the original Dolby Pro Logic format , but the AVP2 added Dolby Pro Logic II (PLII). Original Dolby Pro Logic was 5.1 channel, but it tended to collapse sound into the center channel. Dolby Pro Logic II (PLII) is more natural. PLII was introduced by Dolby in 2000, so it was not in the AVP but was in the AVP2, which came out about 2002.
Since the AVP and the AVP2 AVP2 can decode both Dolby Pro Logic and DTS, although not the new lossless formats (DTS-MA and Dolby HD), if the PS/3 can put out Dolby Pro Logic or DTS (lossy) and you can get it to a S/PDIF cable, then the AVP should be able to decode them as 5.1 signals. On a Blu Ray player, there is an option to but out the lossy (D PLII or plain DTS). DVDs come with the lossy format only.
The AVP2 Manual describes using Pro Logic II, both movie and music modes. The AVP manual is also on the Proceed website.
The AVP2 also added LCPM support, including 24 bit 96 KHz digital signals, by a solftware upgrade. See the review here I cannot tell if the AVP does 2 channel LCPM over S/PDIF or not. It does have AES support from a CD transport, but that is not what you are looking for.
The new lossless formats DTS- MA or Dolby Digital HD can also be converted to LCPM or can converted to analog. As part of the conversion, a multi-channel signal can be converted to stereo. I do not know what the PS/3 does, but most Blu Ray Players, for example, can convert 5.1 DTS-MA to either 5.1 or 2 channel LCPM or 5.1 or 2 channel analog.
The AVP probably has a better DAC than the PS/3, so if you can send a 2 channel LCPM S/PDIF to the AVP2 you can use the DAC in the AVP.
There is lots of detail here. But don't give up on a 5.1 digital signal. It should be possible. Hope I got most of this right. Good luck.
Disclaimer : I have never worked with either the AVP or the AVP2 or the PS/3. But, from what I read, getting a 5.1 digital signal from the PS/3 to the AVP or AVP2 should be possible. And certainly a 2 channel analog should be possible.