In short I think speaker selection and placement are about an order of magnitude or two more important than everything else. If those are the only two things you pay attention to and don't drastically screw the rest up, you'll have a nice sounding system.
Room correction (which is also speaker correction) is probably the next most important thing, although well into optional territory IMO.
There's lots more that I fuss over, but I don't want people believing that they need a lot of elaborate rituals and room alterations to achieve good sound. It's not true, it's counterproductive, and scares people away from this really fun hobby. =)
No EQ on earth will get rid of the reverb in an
empty warehouse. [...]
So EQs can help, but you should also think
about the actual surfaces of the room itself.
1. They tend to be filled with comfy padded furniture, bookshelves, etc. which do a nice job of breaking up high and mid frequency reflections.
2. The brain already performs a lot of "room correction" and it's particularly good at performing it in familiar spaces like our own homes.
3. Most people's home systems (especially those of beginners) aren't putting out the kind of massive low frequency output that's really troublesome to tame.
Of course there is always going to be a room mode or three, usually with a prominent one somewhere in the midbass range.
The thing that might break your acoustics might more often be time-domain issues. No EQ on earth will get rid of the reverb in an empty warehouse. The same is true on a smaller scale in your place. And because it is smaller you will have specific frequencies (room modes) ringing out longer or shorter at your listening position. These are issues you can only fix with actual physical alteration of the space by putting in more stuff and adding absorbers, diffusors and such.
So EQs can help, but you should also think about the actual surfaces of the room itself.