You cannot demux to PCM and create a DVD-A. The watermark is resistant to all tampering.
You can do the following:
1 - Demux & encode to a 24/44.1 DTS-CD.
2 - Demux & encode to DTS-HD Master Audio Lossless & write to a BD-R disc, assuming you can
A - Encode to this format, and
B - Own Scenarist 4 BD edition (legal version, the hacks don't work) or Sony's BluPrint.
3 - Cheapest option of all assuming you genuinely want to simply back the thing up - Demux & encode to DTS-HD MAS & play it on the desktop with the StreamPlayer
4 - Demux & encode to 24/48 DTS & create a DVD-V disc (assuming personal use, as DTS cannot be sole stream on DVD-Video)