The Model 990 lacks an HDMI input, therefore it can't support digital input of multichannel PCM, Dolby Digital Plus, Dolby TrueHD, DTS-HD High Resolution, DTS-HD Master Audio, or DSD.

Since you are connecting the PS3 to the Model 990 with optical, the issue is basically moot: the 990 does support the normal output options offered by the PS3, with the possible exception of AAC. I would recommend choosing either Dolby Digital 5.1 or DTS 5.1 when setting up your PS3's optical output.