Well, I can imagine full sound vs thin is completely personal preference. To me personally a thinner note presentation is more natural for bass and treble, but a thicker presentation for mids is more natural. I've been playing with my new DX90 all day and comparing to ZX1. I find them equally proficient, and even their frequency balance and tonality is very similar being neutral. The biggest difference between them is a thicker vs thinner note presentation, So as I first said, DX90 has more natural mids, ZX1 has more natural bass, treble and sound stage. So with the Calyx M being documented as even fuller sounding than the DX90 I can safely cross it off my list. I just can't have enough of how wide open and transparent the ZX1 sounds, while the fuller sound of the DX90 has more body and weight behind instruments and vocals, it also has a smaller sound stage and less treble airiness than ZX1. ZX1 bass presentation is another love of mine, nothing extra is added at all, bass is extremely defined and textured, where as the fuller sounding DX90 in comparison to the ZX1 has slightly bloated bass. Yet if I had heard the DX90 alone I would have said it has one of the most exquisite bass I've heard, thats how much I like the ZX1 bass. But I would wager most people would prefer the fuller bass of the DX90. It would really be amazing if a dap could provide both of those sonic elements, sound stage and airiness plus weighty instrumentation and vocals. The DX90 and ZX1 actually complement each other very well!