Even with near-fields, a decent room is still a big factor, and as Steve stated, the D/A converters and a set of trained ears is are needed.
All audio-post facilities (& recording studios) I've encountered and worked at have multiple sets of monitors. even in my small 400 sq ft environment, I have three switchable sets and and a few auxiliary sets which are easy connected, not to mention a laptop, cheapo TV and test spkr/amp. If a project sounds decent on all, it's good to go. Minor compromises are almost always necessary to sound good on everything

The effort and expense you devote to audio, I think, depends on how you expect your audio or audio for video will be played. If you are targeting venues with full-range speakers, you need to worry more about the sound design. If producing for the Internet, where playback on laptop or typical desktop speakers not so much. Most of my work for pay is destined for computer playback. I don't need to be concerned about low bass or high treble, but for large venue presentation I do often mix for more dramatic bass and treble. About the room. A reverberant room really makes mixing difficult. Use good headphones to check the audio. I do a lot of voice-over recording. I have a dedicated editing/recording/mixing room about 12' x 14'. Two adjacent walls are treated with acoustic foam panels covering about half of each wall. The other walls have book cases, closet doors, and furniture that breaks up the reflections. Voice recordings using close microphone placement sound great. Another way to tame the reverberant sound was developed by a friend of mine. We were looking for something that would allow us...he's a voice-over guy, too...to record auditions and even tracks for broadcast from a hotel room, while travelling. It really works and has now been adopted by many professional movie sound mixers to record VO on often acoustically bad movie sets. I use it to record narration on corporate video shoots, where acoustics are often terrible. Here is a link to an article that describes the PortaBooth:

http://harlanhogan.com/portaboothArticle.shtml.

Added thought....the cost of the PortaBooth is much less than I spent on acoustic panels for my walls. Another thought. I agree with Steve that if you are doing high-end production you need high end pre-amps, digital converters, and microphones. However, I am impressed with how good on-board audio has become in newer computers. After my last computer build I used the built-in audio for several sessions, while I was completing the final equipment installation. I checked with the audio engineers working with my tracks. They also said it sounded very good, Today, I think the weakest link in the audio chain, after room acoustics, is the microphone. Fortunately, one doesn't have to spend thousands for Neumann or Sennheiser. Marshall (MXL) makes several Chinese built condenser mics that are quite good for a couple hundred bucks or less. There are offerings by other manufacturers in that price range that are perfectly adequate for most producers.

Hope this helps.

It is a fact that most people who will listen to your masterpiece will be using earbuds, and the rest will be on a low end home entertainment system. I have both readily available to test my edits, so my studio monitors are for initial balance and troubleshooting, only.

Maverick, I concluded early on that the way audio sounded when I began editing varied greatly with speaker placement and the position of the editor's head. Unless your editing room is really dead then I'd suggest equalizing it. There are numerous software products that make this pretty simple. Can't recall which one I've used in the past, but it puts out pink noise which you then pull in using a calibrated microphone (calibrated omni mics are remarkably inexpensive). The software computes the room's response as a graph, which will be anything but flat. You then use an in-line equalizer to make the response flat(ter). I found it important to mount the reference mic right about where my head is when I'm in my usual slouching editing position.

From that point on you won't need to worry about how your audio "sounds" on different devices. Flat is flat.

That's not to say you don't need to tweak the audio in your project. One concert hall has a quiet but present 120Hz hum, so I notch it out. Another hall seems to suck the bass out of the recording, so I boost it slightly. And so forth.

As an aside, last year I attended a performance of a choir in a perfectly-cylindrical synagogue here in downtown Portland. That afternoon the sound guy was seen scurrying around the seating area with an iPad running some sort of equalization product. As I mentioned earlier it's easy to flatten a curve for a particular seat, but very challenging to make the sound good for all or even most seats. But after 20 minutes or so he had numerous curves and was then able to select the equalization that did the best for most spots. Very cool.