review my list please

millercarbon pretty much posts the exact same message to anyone here who is asking a home theater question.  I wouldn't put that much importance on his views, unless you are a 2-channel person only.  You can definitely get an excellent multi-channel home theater system.  You have a very good list right now. 

I've tested the 8805 in my system.  It's an excellent processor for the cost.  Large power supply and discrete analog output stages.  Very good bass, punch and midrange body and fullness.  However, it is voiced slightly warm with slightly rolled off high frequencies.  It's a great product.

I haven't heard the MX123, but it's also very well built.  I don't know if it's similar to 8805 or if it has better high frequency response.  Either product will likely,

I wouldn't recommend Audioquest HDMI cables.  They did not perform well for the price you pay.  Audioquest interconnects and speaker cables are good.  So are the power cables.  There will be a million different opinions on the best cables and this is a "can of worms" question, lol.

I would recommend older WireWorld Series HDMI cables that do not have the DNA Helix design.  The older Silver Starlight 5-2 or Starlight 5-2 or 6 are excellent.  If you're on a budget, the Neotech NEHH-4200 HDMI is excellent for under $100 and will perform as good as the much more expensive WireWorld 7 Silver Starlight.

For general music, the Kanta 2 might be okay without a subwoofer.  I haven't had direct experience with these, but I seem to remember they are kind of light on bass (I could be wrong).

The REL subwoofers are extraordinarily clean and smooth.  If you want really good resolution, they are excellent.  If your primary purpose is music, they might be a good choice.  But they are not meaty sounding subs and if your primary purpose is home theater, I would look at a really good vented sub, like something from Rythmik.  There's a definite difference in sound between a sealed sub and a vented sub

You want a preamp with "HT bypass" mode.  The preamp would be connected between the Marantz 8805 and left/right chanels of the McIntosh 8207 amp.  When you switch the preamp to the bypass input, it essentially connects the 8805 directly to the amp, allowing you to do any movie/streaming as normal.

When the preamp is switched to another analog source, it would just play that source (such as DAC or turntable) through it's normal preamp gain stage and out to the left/right channels of the McIntosh amp.