I inquired in the Schiit Magni/Modi thread about the suitability of the X1/Magni combo and was told that the Magni might be too powerful an amp for the Fidelios.
Still, the Magni does have a very low output impedance (stated as less than 0.1 Ohms) so wouldn't that kind of balance out the "excess" wattage? The Magni can supply 1.2W into 32 Ohms, the X1 being 30 Ohms. I'd like to have an affordable amp that goes well with the X1 and also allows some possible more power hungry cans in the future.
The synergies between different spec amps and headphones with different sensitivities/current requirements/etc are a bit unclear to me... Can a high power amplifier really be too powerful for a given headphone even if the output impedance is low?
Head-fiers around here say that the volume on the Magni scales up pretty fast and at the lowest levels there's some channel imbalance so it isn't really suitable for low impedance, highly sensitive cans.
I power my X1s with a Lake People G109 (over 2W @ 50ohms) and it works perfectly fine.