High End System Building. How important is the matching, cabling and room? Thoughts ?

long story short, rooms matter alot, often at least as much as the cumulative effect of all the equipment

Exactly and it is my experience ...

but if you have a bad room, a lot can be done to make the listening experience fairly good, most notably minimizing room effects by going nearfield or semi nearfield

You are right for the "minimizing part...But even nearfield listening as you implicitly suggested   ask for some acoustic treatment of the room to be optimized ...If you want a soundstage over the speakers in depth and encompassing the listener near field position for sure even in near listening you must put some reflective waves to good use .....

room treatments can help in some difficult rooms, but often a very bad/weird room just cannot be handled just by treatments

This is why in my "difficult" past room i used not only passive treatment with materials to reach a good ratio between dispersion , reflective areas and absorbing area and their location , but it was not enough ... I used ACTIVE mechanically tuned devices called Helmholtz resonators in a grid fashion all around the room to change the zone pressure distributions to my liking ...It was not esthetical , you needed a dedicated room but it cost me nothing , it was fun to experiment and the results were stunning ...A soundscape encompassing my listenin position at peanuts costs ...

I’m going to get straight to the point. A lot of us are plug in play. We can’t do anything to the room depending on your living and family situations. If you want to spend less you can. You can improve your room using a number og @mahgister suggestions as well as many others. But at the end of the day. I been doing this a long time now. I want to get my hands of the best equipment I can afford. Some people spend on luxury cars. I like Audio and I’m going to use what I learned to seek out the best equipment, synergy and cabling possible. I will build my system on those foundations. I can’t do anything to my room. All I’m saying is that you can get great sound out of a bad room. You just got to pick the right things to get you there. My system will sound good almost anywhere you would probably put it. Do what makes you happy. If you don’t like spending on high end stuff then don’t. But based on what I’m experiences in my home environment I’m extremely happy with my set up. I will keep doing me. There is nothing like well designed gear that eliminates noise and distortions and is still musical. My journey has placed me at the point I’m at and I’m happy. I’m listening to some beautiful Ahmad Jamal as we speak.  The piano sounds amazing!

It sometimes almost reads as if there is a prevailing school of thought here that is that if you don’t have an acoustically treated room it just doesn’t matter what gear you put in it because it is all going to sound bad.

I don’t have an acoustically tuned room, and I have no doubt that my system would sound better if I did have one, but I also know that even in a bad room I can hear that different components produce different quality of sound.

@calvinj 

seems to me that even though you started this thread asking for others' input you are here to speak rather than listen...

i guess that's fine, to each their own as to why they come to this forum

The room has a significant effect on sound. This has been known a long long time, nothing new here. We all have different rooms, and different amounts of control as to what we can do with room acoustics. Regardless, we can always get good sound in any room, even at low cost. Some speakers are less sensitive to placement and give more/different options. Hopefully we are all enjoying the music on our various systems...