I have here M0 side by side to Mojo and AT-PHA55BT (BT receiver with warmest and bassiest sound of all 3). Also R2R11 desktop dac/amp which is warm and bassy as well..
Now, Mojo is the brightest from all these. M0 is closer to it then to those bassy amps, but it is definitely not bright, it just sits on the sweet spot. That is the tonality.
Sound of M0 is a little more aggresive and dull than that of Mojo. But the main difference is that Mojo sound technically much better with High impedance (300 Ohm, 600 Ohm) open headphones. It is a night and day difference. 150 Ohm headphones sound close to each other with M0 and Mojo. Mojo still is a bit crispier and less dull, but not much, its already sounding very good with M0. There is chance M0 can sound well with most headphones tonality wise - if it is bright or dark sounding headphone, you will only miss that last bit of excellence. On the other side Mojo is brighter by design and sounds too bright with bright headphones.
I would recommend Mojo over M0 with headphones with higher impedance than 150 Ohm, when their sound is warmer and bassier - not neutral or bright. Mojo is very powerfull and can drive such cans with no issues and it will not go against that coloured character.
I would recommend M0 with headpohones of lower impedance, or with earphones with price tag 350 USD or less. With more expensive earphones, you will hear difference, but I am not saying that Mojo would be the right choice here - there may be more balanced, musical, fuller sounding DAPs out there. It all depends on the tonality of your IEM. Mojo's super traits are: make bass tighter, make highs crispier, make mids cleaner, make placement of notes more precise, make overall sound very high-tech. Negatives of Mojo are: make space narrower, make sound less laid back and show less amount of texture of notes, because it can take away a small amout of bass in the process of doing those sound changes. MO's super trait is: make it sound very well cheap. M0's negatives are: it cannot cross its shade, meaning its sound is not as crisp or rich or relaxed as the sound of much more expensive daps. It is simply jack of all trades.
Now, most headphones these days are warm and bass heavy, so Mojo may work with them very well. Not so much with very clean or very neutral IEMs or with old Sennheiser headphones from 80's. I love those old headphones, and I found Mojo to be too bright with them, as they are designed as not bass heavy as today cans are. Yes, they are 600 Ohm beasts, so Mojo shows its magic. But that is not enough. The main thing that person hears is tonality and timbre, and therefore I may buy replacement of Mojo one day. But it would need to be a beast, because Mojo CAN handle 600 Ohm pretty well.
P.S. have/had all of them.
