I use a Sony STR-DA5300ES which passes all inputs over hdmi. It also has 6 hdmi inputs which is reeeeeally convenient. Sounds good also. It does cost more though, but the Sony ES line seems to be well received by audio reviewers. I believe it has since been replaced with the STR-DA5400ES.
That DA5400ES looks worlds of cool, but best price I've seen is 1400 Euro so its definitely out.
Thanks guys for telling me what I feared about the 520 - that one seems to be out definitely.
That leaves the 606 and the 820. The 606's capability to output analog over HDMI is a plus, but not one that I currently need, and I might very well never need it - worst case I can still plug in Component. Still, I can see this is a big plus on the 606's side. Also, the 606's backside seems more generous, with s-video options for most input types as well as the option for an analog 7.1 input, which is not available on the 820.
On the minus side, I do not like reading about the 606's heat and power consumption. It appears to be twice that of the 820, which is a big downer for me. Could very well be that this is partly caused by things like analog to digital upconversion, but my old amp was already prone to overheating under certain conditions (good self protect system though) and electricity is expensive. This for an amp that's almost twice the weight of the Sony (15kg vs 8kg?) makes me wonder.
From the various reviews I've tracked down across the web, the 820 seems to score pretty well on most counts otherwise, but so far for me it's a tough choice now. I also found the 820 for 324 Euro inc tax and shipping, vs about just under 400 Euro for the 606. That might not matter too much though, but still.
The heat/power thing is definitely something important to me and I'd like more information on it.