[Kepic]

Hi, I will get my US Pro 900 in days, and I'm currently looking for a portable amp / dac for it
 
my source would be my Macbook pro and iPhone
 
my budget is $300 max
 
I listen to a lot of electronic ( techno, electro, house, electronica ), some alt rock, some soundtrack ( alexandre deplat) and a lil bit classical
 
any recommendation? 
 
I already bought a fiio E5 for casual use with my iPhone. but still looking one for my Macbook. 
 
I'm now locking down to a second hand Apogee duet. but still wondering if I can get more with that budget? 
 
or is the internal dac good enough for US Pro 900 and need an AMP only? 
 
I post this under the portable is because I want one that can be carried at some occasion.
 
any reply will be appreciated
 
Thanks in advance!