Voice and instrument image bunched in the middle??

You do not describe your equipment so it is hard to understand what is going on. It can be a tweak for speaker placement, changing a capacitor in the preamp, etc. Have you heard the same recordings in a different system that had different results?

Make certain that your speaker cables are each going to the correct speaker. That has often been the cause of the problem for me.

Once you have tried all the above suggestions to no avail, take into account the effect your room has on sound. Room treatments such as absorption and /or diffusion may help.

Using center panels on the wall behind your system often can improve focus and image. Absorption in corners behind speakers may tighten bass. Panels at first reflection points and rear wall will absorb standing waves.
But first you need a good reference recording.

If all of your connections are proper, try the Sumiko Master Set Method of speaker placement. Works with any system and in any room.

There are so many things wrong with everything it almost defies description. I refer you to my new article, "What's Wrong with CDs and Why do they Sound So Horrible?"

Www.machinadynamica.com/machina35.htm