Speaker Balance

I played the channel balance track of the XLO/Reference Recordings Test disc and heard the following, left channel information is further to the left of the left channel speaker than the right channel information is in relation to the right channel speaker. The right channel image sounds like it is more "bound" to it's respective speaker.

My left channel speaker 27" away from a 4' high wall that is open to another room located on a level 4' higher than my listening room.

The right channel speaker is 27" away from a wall with a large amount of glass window area. The windows are treated with Marigo dots. There are also vertical blinds on the window.

I do not toe-in either speaker. A knowledgeable user of this same loudspeaker recommends this setup, although he is not aware of this issue I seek advice about.

Any thoughts on how I can achieve better balance of the images of the two channels? I assume there is a great difference in the way sound is reflected of each wall due to the extreme differences between the two.
It is apparent that your problem is associated with high frequency sounds reflecting off of the side walls. I agree with your friend. Here is a radical expirement for you on toe in - you can use it as a starting point. If your speaker location is about 25 degrees in from the direction your speakers are pointed, toe them in til they are 25 degrees past your listening position and see what your hear then. Assuming you have effectively tuned out the 1st sidewall reflections with that manuever (you will be surprised at the good effect it can have on pin point imaging) you can then toe them incrementally back toward the listening position until you like what you hear. Gsreat tweek - its free. Enjoy.
Did you try swapping the speaker cables to make sure it's not an equipment imbalance instead of a room imbalance. If it is a room problem sometimes you can alter by moving the speaker only a few inches. From your listing position use a tape measure to determine the exact distance to each speaker. To perform this measurement with only one person, I use a folding chair placed on my listening chair and use a close-pin to clip the end of the tape measure to the folding chair and then measure the distance. This should be exactly equal. Experiment with toe-in using a laser alignment tool or a laser pen. In some cases the toe-in will need to be different for one speaker vs the other to obtain the soundstage correctly. I hope this will help you out.
The visual "center" of the room,may not be the acoustic center.You will probably need to move the speaker that is having trouble imaging outside the panel further away from the wall.Be careful using absorbative materials to "damp"first reflections.This will have a tendency to reduce your hieght cues.Think of it as three panes of glass {left,center,right}.Too much toe-in,lateral spread will diminish.Not enough and center-fill will be lacking.Most rooms are odd.You may wish to eliminate the corner effects on the side without lateral spread.Good luck!
Room treatment might help.
It could also be that one speaker is closer to you than the other. Try moving the right speaker back/forward an inch or so.
Hi Wellfed, wish i could help. I have come across these kind of problems. Ya gotta keep moving them around listening by ear. You may be surprised how long, how frustrating this can be. You might find that your speakers look so out of whack from one another and think that this can't work. But it just might. Your situation may need a bit of toe in. Sometimes there are no rules other than experiminting with room placement or room type traps. I hope your speakers move very easy. Work, work ,work, until it locks in. I don't envy you but i wish you the best in this tough situation. Your last sentence is very true and maybe this is what needs to be dealt with. I hope you find that perfect fit.