I have a Denon 3803. It meets some of your requirements, but not all.
I'm especially impressed with its usability. It seems like Denon really thought about things from the user's perspective. For example, it remembers with surround mode or DSP setting you used for each input and for each sound format (i.e. DD vs. DTS; DD 5.1 vs DD PCM, etc...). So if I play a DD 5.1 signal, it plays back direct, but if I play a DD 2.0 signal, it switches to Dolby PLII matrixed surround automatically.
I think that it supports both U.S. and European voltage and has a detachable power cord, but it's been a long time since I was back there.
It has 7.1, but it doesn't support PLIIx, which gives stereo surround-back channels. Only PLII, which has dual mono surround-back channels. It also has the option for A/B rear surrounds. In other words, you can install two sets of rear surrounds and use one for movies and the other for music, for example. Alternatively, you can use the second output as an amplified zone 2 output.
Since the 3805--the successor to the 3803--came out, 3803s are marked down a lot. You can surely find one below $1,000 U.S.
It does have video inputs and switching, although you don't need this.
It has 2 optical and... 5? I think 5 coax digital inputs.
I don't think it's THX certified, but it does follow THX recommendations in areas such as bass management (adjustable 80Hz crossover, etc...) It might be one of those devices that meets THX certifications, but the manufacturer didn't bother to go through the THX certification process due to cost, etc...