I agree with GMC that one of the speakers may be out of phase with the other. On the other hand...
If I understand you correctly, you are saying that one of the speakers has 18ms of delay relative to the other speaker. If that is correct, then I think that could be causing both your imaging problem and the "reverb" effect you described. Why don't you try reducing the delay in increments of, say, 4ms and see if anything improves.
BTW, 18ms seems like a lot. Can you describe your room and speaker layout? Is it highly asymmetrical?
Bryon
If I understand you correctly, you are saying that one of the speakers has 18ms of delay relative to the other speaker. If that is correct, then I think that could be causing both your imaging problem and the "reverb" effect you described. Why don't you try reducing the delay in increments of, say, 4ms and see if anything improves.
BTW, 18ms seems like a lot. Can you describe your room and speaker layout? Is it highly asymmetrical?
Bryon