fyi, Performance is great on a large, quality MicroSD card. In addition it is the best/cleanest path for file based digital music to your DAC. On my Rivo+, I am running a SanDisk Extreme PRO microSDXC 1 TB A2, Class 10, V30, U3, 200 MB/s Transfer. It holds all my ripped SACD and CD disks in .dsf or .wav file format. It is super fast to access and queue up. As you already found, rescan is the mechanism to insure you realize any updates on your microSD card.