[hmp406]

 
Macbook Pro -- Headroom Micro DAC -- Little dot I+ -- Grado SR325is
 
What should I change the little dot out for?
 
Best,
Harrison
 
(or should I make a different move?)

 

[gtube]

Since you use Grado, I would not recommend Musical Paradise MP-301 MK2 which is used to drive >=50ohm headphones and speakers. Check with Woo Audio. They make good headphone amps too.  

 

[hmp406]

as the animaniacs would say:
 
hellooooooooo, nurse.
 
goodbye, wallet.

 

[Tribbs]

I to have the Little Dot I+ and now bought a Sheer Audio HA-006++ (DynaLo).
 
You probably saw these threads already but just in case...
 
http://www.head-fi.org/t/576931/which-amps-to-consider-for-grado-sr-325i
http://gilmore2.chem.northwestern.edu/projects/showfile.php?file=gilmore3_prj.htm
http://www.head-fi.org/t/461997/lost-link-to-a-dynalo-amp
 
An interesting article on the effect of headphone output impedance on the apparent frequency response of a headphone:
http://www.soundandvisionmag.com/blog/2011/11/14/output-impedance-show-and-tell?page=0,0
 
Grado 325is impedance graph

=390]http://graphs.headphone.com/graphCompare.php?graphType=0&graphID[]=390