Best Smartphone For In-Ear Phones?

[jooppi]

I'm due for a smartphone upgrade with at&t and I'm choosing one based off of the audio quality. I don't know anything about audio, so maybe you guys can help me choose one without getting too technical.
 
-I use IEMs - Astrotech AM-90s.
-The speakers on the phone aren't important to me.
-I like android. I'm going to root it and use poweramp for the media player.
-Budget is $150 with a 2yr agreement.
 
 
Here's what we have to choose from
http://www.att.com/shop/wireless/devices/smartphones.html

 

[raclimja]

there isn't any android(newer models) i am aware of that has decent audio quality since the WM8994 era (galaxy s w/ voodoo sound).
 
the only remaining contemporary smartphone that has decent sound quality is the iphone 5s or iphone 5c which uses Cirrus Logic 338S1201 which is on par if not better with the legendary Cirrus Logic cs42L61 which is found on iphone 3gs and 4 (iphone 4s and 5 has mediocre dac).
 
android solution on the other hand has gone down the hill in terms of sq.
 
current incarnations like WM5102 (which is found in international SG4), WM5110 (which is found on LG G2), WCD9320 (which is found in Note 3), and S600 dac (found on htc one and us variant sg4) are mediocre.

if you want to go Android route, i suggest you just get a USB OTG cable and get something like Fiio E07k or Fiio E17.

otherwise, you are stuck with Apple 5s/5c

 

[awayeah]

I suggest one of those:
 
Samsung Galaxy S4 Active
HTC One mini
 
Both have great audio output for smartphones.
Technically (SoC, microSD, battery) S4 Active is a bit better.
HTC One has higher maxium volume (built-in amp).
 
I'm currently using HTC One (practiacally the same audio output).
 
I have the following IEM's:
Klipsch X10i
NuForce Ne-700X
Monster Gratitude
Musical Fidelity EB50
Phonak Audeo 111
Sony XBA-3iP
 
It sounds great on Phonak and Klipsch. Rest is ok. The only problem I've had was with Sony (but that's due to low impedance - FiiO Rocky solved it and they sound great).
I compared the audio experience with Galaxy S4, IPhone 4s, Sansa Zip, Cowon C2 and Fiio E18.
I can strogly recommend it.
It should pair well with your IEM's.
 
You can look up almost all smartphones on gsmarena (they do test audio outputs).
Hope this will help.