Ok guys, I have very good news. I just bought the new Sandisk Micro Sd with 400GB storage capacity and it works like a charm with the Cayin i5! (it scans everything on the card and the read speed is AWESOME), which rises the player max storage capacity to a real 400GB! (The Sandisk micro SD actual free space is 366GB). Compared to my Samsung 256Gb microSD the read speed was definitely improved (I have every album tagged with the cover art at 600x600) and every single cover art pops really fast in the albums tab, yet the write speed is still better on the samsung. I can confirm this is excellent news for playback in the Cayin i5 since right now aprox 6000+ lossless tracks could be stored in the device.