Yes it may change in time due to burn-in. The reviewed unit had more than 150 hours of burn-in.
And here it is ZX2 rank in my list:
http://www.head-fi.org/t/751068/dap-challenge-chart-including-23-portable-sources-sony-zx2-added-more-to-come
Nice list.The only one missing is Cayin N6 and you have full house