Can I Improve Sound--Macbook Pro as Music Server?

My system:

NAD M2 (amp/dac)
Audiphilleo2 spdif to usb converter
Macbook Pro (2012) /Furutech Formula 2 USB cable
Itunes- Tried Puremusic demo and thought it was actually less impressive than Itunes
Speakers: Mirage OMD 28

Files are all on the Macbook Pro- don't have an outboard drive yet

Recently switched to ripping in AIFF after starting off with AAC

My system sound lacks a little in weight / clarity/ resolution

What can I do do beef up / clear up the sound with my Macbook Pro?

What about the optional power supply for Audiophilleo2?

Have you tried Audirvana Plus? It sounds different from PureMusic. You may like it better. It has a 15-day trial as well.
Put your music files on a separate drive and use a firewire connection. (It's important to use a different bus connection than what your music drive uses). Max out you memory, 4Gb at a minimum. Only use non-data compressed files. Try Pure Music again and set it up for memory play with factor of 2 upsampling.