Thanks for the replies until now.
I should have added perhaps that I don't own a BD player yet. I use my htpc for playing everything (with Winamp, foobar2k, MPC and PowerDVD Ultra). Although I have a Marantz dvd/cd player I hardly use it anymore.
With my present, maybe faulty, receiver/system I have connected my videocard directly to the HDMI input of my Sony HD Bravia TV and I use the analog outputs of the soundcard connected to the multichannel inputs of the receiver. This way the software player does the decoding and the soundcard does the D>A conversion. So actually the receiver is "only" for radio and for amplification.
Although I may buy a BD player in the near future, at the moment I don't need all the HDMI optiopns, nor the HD Audio decoding. So maybe Nomo's suggestion is a good option.