"Output Power: 200mW/300Ω, 400mW/60Ω"
That's just telling you how much power it's putting into 60ohms. That's not the lowest it will go. You can plug IEMs into it if you want.
The M-stage's actual HP jack output impedance is 5 ohms.
The M-stage is probably a little overkill for the X1 though. They're not that hard to drive. A think a cheaper amp would work fine with them.
Thanks for the explanations.
I must consider to buy stronger amps for my next cans, probably k712 or hd650.
If I buy cheaper less strong amps now for X1, then I must buy another amp later. More money to spend.
Too bad I can't find magni/modi seller here. I must wait for my brother from USA to visit me here next year.