Wolfson WM8740: 540C vs. 640C vs. CD73 vs. Apollo

All four of the following CD players use the Wolfson WM8740 DAC: the Cambridge Audio 540C v.2; the Cambridge Audio 640C v.2; the Arcam DiVA CD73; and the Rega Apollo. (So did the Arcam CD93, now out of production.) Other aspects of these designs vary, such as the number of DACs used, CD drive, power supply, and chassis; and these players are not being marketed in the same price range. In what ways do these CD players sound similar to each other? In what ways do they sound different? How important are the other aspects of these designs, aside from the DACs, to the quality of the sound they produce?