Hello tfromcfla,
I have a Sony SDP-E800 which is very similar to the SDP-EP9ES, except its missing the additional 5.1 input, and it does only Dolby Digital and Dolby ProLogic.
But it does loop the DTS signal to the digital out that another unit can decode it. And it doesn't accept 96khz signals.
There was released a newer processor called SDP-EP90ES, but only MPEG multi-channel decoding was added, again no DTS.
if you need the manual
SDP-EP9ES
https://docs.sony.com/release/SDPEP9ES.PDFSDP-EP90ES
http://pdf.crse.com/manuals/3862881121.pdfGreetings