Limited soundstage between speakers

Reflections must not be suppressed completely OR enhanced over absorption ...

Yes, like in a concert hall. Too many audiophiles have over damped rooms.

@mglik 

How did you diagnose the problem and decide to use a Zobel network? I've seen the Deulund-Mundorf Speaker Purifiers for sale.

I dream of a dedicated audio room.

I dream of obtaining a 3D enhancer BAACH dsp crosstalk cancelling component. Reviews extremely positive

The best way to investigate this is buy a couple of good absorptive panels (a pair of the ATS 2 inch deep, 24x36 panels off Amazon), hang them on the wall at the first reflection points and see what happens. I’m betting your imaging improves dramatically. It’s not an expensive experiment and can be reversed very easily.

Brad

Buy Magneplaners.  Have an expert set them up IN YOUR ROOM.

If they do not give you what you are seeking, I have no further suggestions other than change your hardware or sources.

Cheers!