Originally Posted by HockeyoAJB
If you are using a 7.1 capable receiver, but only happen to have a 5.1 speaker setup then it should be able to downmix 7.1 PCM to 5.1 speakers. However the EQ might be screwy as your software is preforming its EQ under the assumption that there are 8 channels when there are really only 6 being output. You would likely get better results by telling the software to downmix to 5.1 before EQ is applied.
If your receiver is only 5.1 capable and you are feeding it 7.1 then it will just discard the extra 2 channels worth of audio information. So, again, you would be better off having the software downmix to 5.1 before EQ is applied and certainly before the audio is output.
Both scenarios assume that you are passing the audio from the PC to the receiver over HDMI. Normally, the PC and receiver should be able to sort this out on their own during the HDMI handshake, at which point the receiver will tell the PC that it can only handle 5.1 audio. Obviously, if you are using analog connections then you would also want to do the downmixing in the software as you could then keep the signal in the analog domain after the initial DAC, so as to avoid multiple conversions.
Thanks a lot for your reply. In my case, I have only a 5.1 capable receiver. I guess I was under the mistaken assumption that the receiver would handle 7.1 bitstreamed audio by performing a downmix internally to 5.1. I wasn't aware that the receiver would simply discard the extra channel data.
And yes, I do have everything hooked up via HDMI from my HTPC to my receiver. So if I want to perform the downmixing using LAV Audio in MPC-HC, what options should I use? My windows driver for my HDMI output (audio) is already setup as a 5.1 configuration. In LAV Audio...I believe Matrix Method (or some similar option) is set to None.