have this dap for about 6 mos. bought am3 which made difference with my audio technical ath mx 30 40 and 50x series. the problem imo about audio equipment is everyone has different hearing. some here hear at different ranges and tones what may sound superb to one may just be ok to another. the big improvement with this dap was android 5.1 update. The x7 is now more smooth operating. also a footnote if you are having a problem updating from 4.4 firmware using download tool for windows 10 it worked for me temporarily disabling anti virus to download...