Moving the sweet spot

In reality there can only be one ultimate listening position where phase, timing and frequency response are all correct. Everything changes as you move about. Some systems are better off axis than others but none are perfect off axis. 
All systems are going to have a spot where they sound best but very few are going to have an ultimate listening position where phase, timing and frequency response are all correct. Phase is easy. All you have to do is be equidistant from both loudspeakers, timing depends entirely on the design of the speakers unless you have subwoofers which make things more complicated. Frequency response is the big outlier. It can literally be all over the place. You are lucky to get it within +- 10 dB at the listening position. Most but not all of the trouble is below 150 Hz. This is the variable that at first listen makes systems sound so different. It also makes bass difficult to evaluate. 
The three variables are easy to measure and adjustments can usually be made to optimize them if you have digital signal processing. If you do not then you are stuck with whatever your speakers do in the room you have which may be good but it will never be optimal. I do not know about everyone, but I can not get a system running optimally by just using my ears. You can get a great measurement system $300 plus your computer.
IMHO this is the best way to get the optimal performance out of any system and the best listening position. Ultimately, you should just hear individual instrument and voices, not loudspeakers. 

Minimize the reflections in the room. Then sit in between with the speakers facing straight or slightly angled towards you.

Near-field listening is ideal for picking up details. 

inscrutable, no balance knob, thank you for your idea with first reflection

Maybe silly, but do you have a balance control to play with?

+1 MC. That was so funny I had to give you props.

I wonder how many of us have hearing damage in our right ear because of driving with the nagivator?

I wonder how many of us have hearing damage in our left ear because of driving with the window down…

lowrider57, Yes (4) Cathedral Panel, facing the rear and front wall on the lenght of the room.  I found it help to have a better focus sound.  Thank you

audiosens, do you have any room treatments? Absorbion and diffusion in key areas can help immensely.

Sorry not secondary reflections, 1st reflections.

Cheers George

audiosens OP
I was just walking behind my sweet spot chair, and I had noticed that I can hear more of the high frequency

You were probably on axis to the tweeter behind the chair and off axis in the chair.
Also use a mirror get your better half to go along the side walls with it against the wall till you see the tweeter in the reflection from your listening chair. Mark those spots on either side and hang something thick and soft there, to stop any secondary tweeter reflections which smear the highs reaching your ear.
You can also do the ceiling (and floor if hard surface) if your up to it.

Cheers George

@audiosens, that's great and you're very welcome.
The tweaking you've done is really what I would call speaker placement 101.

You have no idea how many times I've repositioned my speakers a half inch at a time to find the sweet spot for my room. 

lowrider57, I moved my chair back, opened the angle of the speakers, and re-installed the ByBee QSE under my integrated amp. So now, I have a realy most pleasant sound.  Thank you.

millercarbon,  I think you are right, it happens for most every one of us... with the age.  Thank you

This is tech talk. Map out your room modes and it will be obvious that cancellation only happens at certain locations that vary by frequency. What happens is the waves reflect off the walls, come back and where they meet they either cancel or reinforce.

This happens all the time everywhere, but really is only audible in rooms with almost all smooth unbroken walls. Because otherwise the waves hit uneven surfaces, bounce off in different directions, and the result is the reflections become diffuse. Which is why surfaces deliberately designed to do this are called diffusers.   

This never happens in as you say "an open space". So we can cross that one off the list and we are left with, "and my left ear is not as good as I was young."

You may want to experiment with different chairs, too?
And when you identify each chair's respective strengths and
weaknesses, you can adjust for effect.

You know Master M has two different spots he listens to. I can't remember the reason but both have their strengths and weaknesses for listening.

Maybe he'll chime in..

Regards

Yup lowrider57 has got it. Adjust one speaker for one ear. Set the camber, caster and toe in/out THEN closer or further for DB gain or loss for your ailing ear.

I found the biggest thing about the seated position is height in relation to the Bass roll off and the HF being there but not beaming and boiling your ears to death...

Painters tape a square and a tape measure. You want to get real picky laser line placement or string lines to your head in the seated position..

You can get REAL picky...

A mic stand and some tape to hold the string lines at the speaker and stand.

In your original listening position, have you tried toe-in to the point that the drivers are facing you?
Or tilting the speakers back (rake angle)? The angle would depend on the size of of your room.

It's tricky. Sweet Spot A is better at different things than, say, Sweet Spot B.