Klipschorn Imaging

Well, you don't have much flexability in positioning this speaker, to get stereo "Image" its all about acoustics and placement, and maybe more importantly in this case Position. Not only are you forced to put these in your available corners, but also the distance of those corners and where your seating position is normally is where it is and thats it. Not a ton of choice, this is why I believe ultimately many take K-horns and finally put false backs on them to simulate the corners which I guess you are doing as you say they are only 10 feet apart and its a 25 foot room?

Not everybody has the problem possibly, but obviously some of them do. It has way less to do with a magic cable, or source, or tube, or amp to correct this in most cases. Probably the only way to move this "Image" electrically without physically moving the speaker is to get the right crossovers that might open up and help the speaker more and I am not saying this will correct it, might just sound better. There is no right answer on that depending on the room and type of electronics used all add up to the ultimate results.

Room tuning could help if you can do it, I suggest some diffusors or something to try and break up the sound at the reflection points, but again this could be tuff if your dead in a corner somewhere with nowhere to place devices and treat it.
Good Luck