Portable amp/dac recommendation for Hifiman Edition X

[Sir Sanders Zingmore]

I have a pair of Hifiman edition X planar magnetic headphones.
I mainly listen on my iPhone and I find that it lacks enough power to drive them properly.

Is there a portable device that can go in between my phone and my phones that will give me more power and possibly a better DAC.
Something along the lines of a Chord Mojo but cheaper?

Thanks in advance!

 

[maxxevv]

NX4 DSD.

 

[Vatnos]

GeekOut V2+ sounded pretty good with them.

 

[Sir Sanders Zingmore]

GeekOut V2+ sounded pretty good with them.

Thanks for the suggestion.
However, I'd prefer to go with something that has been measured (I can't find measurements for the GeekOut).
Also, it is quite a lot more expensive than the Topping NX4