Which source can you use with HTPC with a multi-channels DAC output?
Only file players like jriver ?
Do streaming apps like Netflix, Disney plus work too?
For the SDP-55/Dante you can use any source which will output over HDMI (It is fine with it being HDCP / Copy Protected too). There is up to 16 channels of output but they are fixed at 24/48 (Licensing rule for HDCP content and also the limit of Dirac).