In my quest for a NAD stack I pur­chased a 523. The good thing about just buy­ing stuff be­cause it fits on the stack is that when it's hooked up it's sur­pris­ing how con­ve­nient it is when you ac­tu­al­ly start to use it. I've nev­er won­dered why any­body would want a 5 CD chang­er, but when there is one at your dis­pos­al it sud­den­ly be­comes clear that 5 CDs add up to about 5x74 min­utes, which is like 6 hours of mu­sic. So at the start of the day you pop in 5 CDs, prefer­ably from a mul­ti-disc col­lec­tion like Liebrand's mix­es and press play. And then it ro­tates 4 times as fast as the earth around it's axis, de­liv­er­ing 6 hours of mu­sic. (Of course iTunes can go on for months, but I find it a bit dis­turb­ing to be re­mind­ed at some point that you will prob­a­bly die be­fore you've played all tracks in your li­brary again and miss out on stuff like Tec­no Bre­ga).