I have both the Ibasso DX90 and Fiio X3 second generation. I like both but prefer the sound on the DX and the UI/size on the X3. While sound is the most important....I wonder if it is worth double the price. Also I think that I may like the sound of the DX90 better because I know that "it should". I prefer progressive type of music to metal. Examples of most listened to are...Rush, Dream Theater, Marillion, Police, Dire Straits, Deep Purple, Coheed and Cambria, Old Foreigner, ELP, Genesis, Journey, Black Sabbath, Judas Priest, Metallica, Led Zeppelin, Pink Floyd, Yes and Guitar greats like Yngwie, Satriani, Vai and Eric Johnson. Which unit is more suited to this type of genre. My ears say Ibasso and my wallet says Fiio, but I am no golden ear. Also I am 50 and I can tell no difference between Mp3 320 and 96/24 Hi res type music. Is either unit better at playing back Mp3? I own Audio Technica M50x (closed type), Grado Sr 325is (open), and Shure Se 535 iem plus assorted bluetooth units to go with my phone when being more active or needing wireless. I did get the Ibasso for $479 that included the Dignis Leather case, wall charger, and 128 gb card as extras and the X3 for $199. Is it that this type of playback units are in their infancy or they continually evolving? Fiio seems to move more quickly to improve vs Ibasso.