Sure thing boss................
My warmer FiiO E17 dac hooked via my Schiit Vali amp takes these Logans to another level for me sonically due to the transparent yet slightly warm sound.
Much better than my ipod nano via venturecraft go-dap combo cuz that setup sound much leaner and more fatiguing. So based on apples use of dac/amp chips these recent years the iphone 5 should have a more refined cirrus logic dac as compared to the nano, but still the apple house sound these days tend to be more clean, lean and clinical.
Never owned the FiiO X3 but their amp/dac section should gel really well with these Logans in theory, as compared to the cleaner/ leaner sound of the ibasso DX50s.
Maybe some X3/ DX50 owners can chime in and give us some impressions of how these Logans gel with those sub $200 DAPs. :)
Or maybe you can just get one of FiiOs new sub $200 external amp,s or one by JDS. Can't really go wrong with any of them tbh.
I'll offer up an endorsement for the JDS C5...neutral and pairs very well with the Mikros.
Almost bought the HD650--for the third time--and the AKG K812, too, but thought better of the latter.
Would really like to find the DT880/2003 version.
Might bite the bullet and get the HD800.
The Mikros 90 sound really, really good on my office rig, driven by the Beta 22 and wired with the Auvio.