This is great information antani. Since I'm also using an HTPC exclusively as my AV source, this may be the next configuration I look at implementing. Thanks for posting.
By component I meant SPDIF; sorry for the confusion. My receiver calls SPDIF it's "component" audio input. I think it makes sense that the analog outputs need to be used when using the PC as an EQ. Thanks.I don't understand exactly what you mean by "component". In order to use the HTPC as an equalizer you need to use the analog 7.1 outputs of the audio card. You cannot use the spdif. By the way HD audio streams cannot go through the spdif and currently there is no audio card with HDMI 7.1 outputs.