Which Amp for AK100ii

I am new here. Looking for a good advice.
I have an Astel and Kern AK100ii DAP as my main music player.
I am also looking to buy Sundara headphones that are hard to drive.
Looking for a recommendation for an Amp that will pair well with my setup.
I am hoping to not have to buy an external DAC, and just usd the one built in AK100ii.

The budget is under $300 for a new Amp.

BTW, AK100ii is also capable of outputting the signal in balanced way.

Is it worth getting Drop AAA THX 789 and using the balanced output put from AK100ii to its XLR input?

Or am I better off just using single output and getting Atom Amp?

I sm looking for the best bang for the buck and cleanest, clearest and most dynamic presentation of the sound.

Thoughts? Recommendations?