I have owned the T-1Ds, the 3.5s and now own 3.6s. I've owned Magnepans for 40 years
A solid central image is not the speakers strongest point due to their physical size with the side by side layout of the drivers next to each other. IMHO, the T-1DS were the worst at this and they have the same panel configuration as your IVs.
You can improve the central image by putting the tweeters on the inside, but I'm guessing you do that now. Fanatical positioning with a laser distance meter from the listening position also yields very notable improvements in focus.
I wouldn't recommend another speaker, so I can't tell you what else to buy....
A solid central image is not the speakers strongest point due to their physical size with the side by side layout of the drivers next to each other. IMHO, the T-1DS were the worst at this and they have the same panel configuration as your IVs.
You can improve the central image by putting the tweeters on the inside, but I'm guessing you do that now. Fanatical positioning with a laser distance meter from the listening position also yields very notable improvements in focus.
I wouldn't recommend another speaker, so I can't tell you what else to buy....