HD-audio decoding

Hi guys
I have a PC with an Asus Xonar DX sound card. My old speakers stopped working (warranty expired). I am planning to buy a speaker/AV receiver set capable of HD-audio processing (DTS-HD MA, DTS-HD and Dolby-HD). My question is, instead of buying an A/V receiver with HD-audio capabilities and then connecting the speakers to it, can I use Power DVD Ultra to playback Blu-Rays and decode all HD-audio formats from it thus saving money on the receiver? Would there be any audible difference in quality?

System config -
AMD Phenom-II 965 3,4 Ghz
Asus 880g motherboard
4GB DDR 3
MSI Nvidia GTX 560 Ti
Asus Xonar DX
Antec True Power 650