I thought this thread was about cabling but after rereading, I'd like to add one more thing that I've found to be a huge improvement that's not cable related.
I've mentioned on another thread how my speakers are made: they're semi-open baffle and have three different sized openings on the rear (you can change the slats which in turn, change the opening) and when I completely removed them, the soundstage took a dramatic turn for the better.
I used the largest slat which had the smallest opening for bass reinforcement since my speakers only go down to 40Hz and then drop off rather quickly. After getting my Darwin Silver ICs, the bass went deeper and was better defined. Playing around with the tone controls on my Marantz added some more welcome bass without any real drawbacks.
Still being on the experimental phase, I went back to direct in (no tone control adjustments) and fiddled with the rear slats on the speaker.
Insert 'epiphany' here.
I'm guessing that when the opening on the rear is larger, the speaker acts more like a dipole and most likely something more that I can't figure out since the bass is better defined and just as deep as before and the images now seem to float, independent of the speakers and not have that projected quality. Details abound and notes seem to dissipate in more directions. The only analogy I can think of is things are no longer congested, which I never thought they were before. There is a freedom and naturalness to the sound that I really enjoy. Interaction between players is more convincing as well since things are a lot more coherent.
All in all, my biggest thrill of the year.
All the best,
Nonoise