Before I tell you the setup I like best, after many years of experimentation, I'd like to first tell you the setup I personally don't like (even though a lot of sound engineers do this).  Two studio monitors, five feet apart, on a desk two feet away from their face.  And NO sub-woofer!  I think they call this "near field" monitoring. But at some point during the audio mastering process, you must crank the music up very loud to set your final compression and to hear how it translates at high volume levels.  You can't do this if your speakers are right next to your ears!  At least I can't.

Maybe this is why the songs I get in for re-mastering badly break up when cranked up loud, and the bass is totally washed out.  They were originally mastered at very low levels without a sub-woofer, and not optimized for loud playback.

I also find it hard determining the overall depth and stereo width in music when the speakers are two feet in front of me.   Which makes sense.  Its like watching a 50" TV.  I want it to be far enough away so I can take the whole picture in.  No one puts a 50" TV on a table right in front of them, yet this is done with speakers.