noromance covered all the "sonic" improvements, which leaves the matter of involvement, immersion, suspension-of-disbelief, excitement, ability to discern the artists "intent" (for those who, Like Art Dudley, think playback equipment can affect such things), and, most importantly, increased musical comprehension (of complex music like Beethoven Symphonies, and J.S. Bach’s Concerto For 4 Harpsichords And Orchestra, the latter placing great demands on a system’s ability to unravel the individual threads of a dense musical weave).
Of course, the quality of a system's abilities in purely sonic terms affects the above too.