New BDP, Old AVR
If you connect the coax or optical digital-audio output from the BDP-93 to the AVR, you won't hear Dolby TrueHD and DTS-HD in their full glory—you'll hear only legacy Dolby Digital and DTS, because coax and optical connections cannot carry the new audio bitstreams. The only way to get the full benefit of the new audio formats in your system is to use the multichannel analog outputs from the Oppo (shown above) to the Pioneer.
As for whether or not you'll hear the benefits of Dolby TrueHD and DTS-HD over legacy Dolby Digital and DTS, only you can determine that for yourself. Some folks say they hear a huge difference, while others say the difference is minimal. I believe it depends in part on the quality of the rest of the audio system and the amount of experience the listener has.
If you have an A/V question, please send it to email@example.com.