Quick comparison of DAC preamp output of Mojo(with Hugo 2 mixed in) vs Questyle CMA600i:
When driving full sized headphone M1060 planars, the 600i has more refinement as does the Hugo 2(which I have recently tried). 600i tend to sounded a bit warm with wide stage presentation compared to the Hugo 2. 600i has more of a laid back treble charactersitics compared to the Hugo 2, and also the Mojo. If you have the 800 or 800s, 600i should help in supressing the peaks in the lower treble region as it is laid back, and especially it's sibilant characteristics. Although 600i sounds more detailed as does the Hugo 2 than the Mojo, it has a bit of a treble texturing that creates a slight faux detailing. It's not the most resolving source I've tried for this reason. Compared to the Hugo 2, it does present a warmer sig, and given it suppresses some peakiness may come off as a tube like presentation in sig although it is solid stage DAC/Amp. In terms of detailing, the definition of both the 600i and Hugo 2 is better, but Hugo 2 can be the most transparent which may not bide well at the output with peaky tracks, and therefore I prefer the 600i than the Hugo 2. 600i comes very close to the Hugo 2 for being less than half the price, but downside is that it is not portable like the Hugo 2 or the Mojo.
I would recommend giving M1060 a try as it does scale with better sources.
Mojo, although lacks a bit on the definition and resolution of sound compared to the other two, interestingly sounds very good out of my studio monitor speakers. I have not tested the Hugo 2 yet with the 305 monitors though. What Mojo does well is punchiness and tightness and how well it controls the planar drivers of the M1060, but with this, it has a more of a forward and aggressive characteristic.
Lesson here is that although 600i better than Mojo for headphones, not for my studio monitors(JBL 305). For some reason, the dynamics and definition is lost using the powered speakers as output. As I've said in the past, out of any DAP/portable DAC/Amp, Mojo has provided the cleanest output to my JBL 305 powered speakers. So, just because a source does well for headphones, doesn't mean, it will equally perform well for speakers. Just to add, I've used balanced output of 600i and headphone out of Mojo. This is also a lesson that balanced does not mean better.
This was quite counter intuitive experience as I hear punchy bass out of the M1060 planars, but not my JBL 305, do I take it that planars are driven better with 600i, but not really for dynamic speakers.