On the rear of the HT-X70, there is an HDMI-IN port that you'd be able to connect to a new Blu-Ray player. Since both audio and video can transfer through an HDMI cable, you should be able to use that input for your Blu-Ray player.
If the DVR is using the HDMI input already, there are no more optical inputs available for the audio, so you'd likely have to choose between the Blu-Ray and the DVR.
Does that help?
I have the following components:
Samsung HP-T4254 Plasma TV
Samsung HT-X70 HTIP (upconverting 5 disc dvd)
Motorola HD DVR
The components are setup using HDMI cables and an optical cable.
Is it possible to add a Blue Ray player to the system and still take advantage of the sound from the HTIB?