It depends on many factors. AC Lines with AC filtering is a must for a natural sound especially from digital sources. But if you speakers were facing each other then I'd say get your speakers set up properly, etc.
You have already picked out cables and equipment without your AC being treated and that could change what cables and gear you use today. Most system don't have the basics down but will go out and compare cables, cords, and gear. I found it hard to tell some differences between some of these items before I had all of the other items prepard for a system.
So the following is what is needed just to get yourself at the starting line:
1 Dedicated lines with AC filtering - see my thread on caps
2 Equipment isolation, speaker spikes, etc.
3 Room treatment
4 speaker placement
Again, once this is all set up, then you can start to pick out all the rest.
Happy Listening