You need to worry about the warranty of the disk more than that of the NAS. Mine is running strong for 10 years. 2 HDDs failed, I suspect because of unexpected power cut.
Yes using 220 to 110 step down,bought it from Radioshack as didn't want to trust any Indian product.
Vali2 is good. Ample power for the headphones and decent power for an old Pair of F&D speakers.
I'm still enjoying the headphones to do an A:B comparison between the Vali2 and my old Bravo...