This answer is 'it depends'.Older AVRs might not do a digital conversion. Older as in, from before 2005 or so. Many could not apply bass management, for example.Newer receiver typically can and do (in order to apply the modern array of digital signal processing that comes with virtually every AVR), but you can also override it to get a 'pure' analog path.
That's how I would do it. I only run an HTPC and a PS3 to my AVR and from that to a 50-inch monitor (no tuners or speakers in it) so I have a similar setup. I'd go with an AMD offering, cause their HDMI audio is better. Perhaps you could wait a few days or weeks until the new 7000 series start trickling down.
I have a new-ish AVR (Pioneer VSX-01 TXH) and it has 7.1 analog inputs, which can't get DSP'd so that leads me to think there's no ADC for those inputs. Stereo analog inputs do get digital processing.
I'm pretty sure any new receiver, even low priced ones and older models support 8 channel LPCM over HDMI.
Is there a specific reason the AMD based HDMI is better?
Regarding older models, in my experience multichannel LPCM was not very common as a media delivery format -- not sure it is even now. So for employing an all-digital lossless multichannel path, we mainly were served DVD-A (lossless compressed and encrypted, could not be passed until HDMI 1.1 in 2004), and SACD (which isn't PCM, and required HDMI 1.2 , from 2005) then Dolby TrueHD and DTS-HD Master Audio (required HDMI 1.3, from 2006).
This answer is 'it depends'.Older AVRs might not do a digital conversion. Older as in, from before 2005 or so. Many could not apply bass management, for example.Newer receiver typically can and do