Can interconnect cables improve sound stage height, width, and depth?

Out of boredom, I swapped out my Darwin ICs for an old pair of Mapleshade copper ribbon ICs and then, a pair of Zu Audio Mission ICs to see what would happen. 

With both of the older copper ICs, I was rewarded with a pleasant, slightly fuller/denser presentation. Highs were recessed compared to the Darwins and it had that nice, reproduced sound to it.

When I put the Darwins back in, the sound became more focused and had that "I'm now in the studio" presentation. The shimmery highs returned, the bass tightened up, and it became much more realistic, in every aspect you can think of. There was no comparison.

Use your ears.

All the best,
Nonoise

You’ll hear more musical info in the areas where you previously couldn’t.
It will be more detailed, have better focus, and be more in balance with what you already hear, giving the impression that it grew.

Just having less toe in with your speakers  will increase the soundstage more than better interconnects. But by all means, use better interconnects.

As for your last question, I use Darwin ICs and they helped "grow" my soundstage. 😄

All the best,
Nonoise