Optimal monitor and mixing position

I'd be curious to know this as well. After paying for a professional to treat my room, with specific advice of how far apart my speakers should be and where they should be pointed, Sonarworks had a very different response curve than the one I received.

There are no set rules, everything is a compromise through in differences in rooms, speaker design, equipment layout and work flow. It really comes down to moving the speakers and listening. You can use the information provided by manufacturers, acousticians ect as a starting point but you would be surprised what a few cm or degrees tilt can make as far as imaging and bass response.

Software and experts operate in the world of generic speakers, you have to have an understanding of frequency response, driver interaction and radiating pattern as well how all boundaries will effect these of your particular model of speaker to make anything beyond a guesstimate.

Now in the world of live sound we have software and measurements provided by manufacturers that help predict a decent response but even then you would be surprised how often small adjustments make all the difference.

Its trial and error IMHO, but as Eric said there are many credible sources of information that make great starting points (room calculators etc). There are so many unique variables to each and every room including the actual construction of the room itself. For example, was your room built with cheap ass 1/4" drywall that wasn't properly screwed down (like my room)? In my case the walls literally shake and that can work against you (exciting room modes) or for you (like a tuned membrane trap dampening low frequencies).

From my experience I'd say setup your monitors as best you can based on the information you have. Do it without a sub at first (if you're even using one). Then take measurements with REW (or another similar program), and start making small adjustments to positioning of the both the speakers and sometimes furniture that may be cause boundary reflections. Compare all the waterfall plots, pick the 2-3 that look the best and choose between them based on how they sound NOT on how they look. Trust me, the best "looking" frequency plot is not necessarily the best sounding one. You have to remember that we don't live in acoustically perfect environments, what sounds "normal" or "best" is somewhat subjective, and our ears are very adapted to hearing things in less than perfect environments. After you've figured the best placement and settings for your speakers add your sub and repeat the whole process with your sub, experimenting with different sub position and settings.

This could easily take you an entire day of work but its well worth it.

The you was meant in the broader generic sense, but to your point.
Even a measured on location with the exact speakers by an acoustician is a compromise based on somebody else’s preference’s. Also we have to take into account that most acoustic measurements are based on average’s and use weighted filters that often hide a problem at a particular frequency as well as don’t really show how a particular speaker is going to image.
Don’t get me wrong I wish all the tools worked better at this, moving speakers around and listening is time consuming and I’d kill for a faster solution!
One thing that I often find that many ignore are the effects of fatigue and power compression. Fatigue is self explanatory but power compression is the effect of a speaker acting as a compressor as the voice coil gets hotter over time or at higher listening levels. I have found it is even more prevalent in compact powered monitors because of the addition of heat producing amps.

At your ears or behind your head? I've heard both.

I'd think the difference would be so small between the two positions that it wouldn't matter much, but I suppose that would come down to the monitor's sweet spots.  As I mentioned in the other thread about the Footprint 01's I auditioned, the sweetspot was probably about 5-6" round at about 3ft away from the speaker, which was ridiculously small and unusable in my opinion.   In a case like that, I'd expect the position could make a huge difference, but literally leaning forward or back a few inches made radical differences in tonality.   

In theory it shouldn’t matter, but in the case of a built in sub we talking about a driver operating a driver over a couple of octaves range and probably a non linear frequency and phase response. Add in room effects and I’ll say who knows? Of course all other variables being the same the same would be true if the sub were side or front firing.

I just read the Genelec monitor setup guide. I was also surprised that they recommend 2"-23" from the wall to the speaker to get rid of the low frequency null point at 1/4 wave. Very interesting. My thought is that moving my monitors might significantly improve the speakers in the room and thus Sonarworks would have to do less, which in turn would give me more headroom. Can't wait to try this out!

I've been tweaking my mixing/monitor positioning for the last year, and all I can offer is what worked for me:

I tried different room percentages, wave calculation tables, etc. and ended up with my PMCs as close to the front (behind computer) wall as I could. I have concrete walls so bass flys around like crazy in my room, and I have these custom built gigantic 7 feet tall corner traps with low GFR absorption. That made the biggest difference in smoothing out the bass in my room by far, even more so than moving the speakers/listening position. I have 4 inch absoprtion clouds and 6 inch first reflection point absorption panels. Having them on separate heavy stands off my desk with Isoacoustics holding them up helped as well.

I also ended up with them about 65 inches across from tweeter to tweeter, which has been recommended as a good starting width. Seems to sound best to me after tweaking. Make sure to get them toed in at 30 degree angles as well; check out an app called SpeakerAngle for your phone to do this easily. Also, moving the computer monitor so that its parallel with the tweeters with absorption on the back of the monitor like Thomas Barefoot recommends actually made a good bit of difference in my stereo image, especially the center. Was pleasantly surprised by that. Hope any of this helps!

That’s awesome, sounds like a significant improvement!