Levinson 390S vs. Levinson 37 + 360S

I have levinson pre/power amps and want to upgrade my CD source from Cal Audio icon II. The 37+360S allows for other digital inputs at a substatial cost difference over the 390S. But does the combination provide better sonic quality over the single unit when they include another set of interconnects? Has anyone done A/B's on these? Does anyone have other reasons to choose one side against the other?