Hold - what you're describing in "bluntness/congestion" in my experience is due to a lack of a good power supply. Could be in either or all of your components. A good power supply gives better depth, space, layering, dimension, seperation, see-through holographic imaging. An inadequate power supply will tend to roll everything up into "one" and diminish the spatial image while inducing congestion, especially with complex passages. Stock cheapo power cords and AC/DC adapters are common to do this in my experience.
From your set up, your PC's power supply in a non-issue since you use a squeezebox and the audio signal is essentially out of the PC's noisy environment and fed to the squeezebox. Now you only need to worry about the signal from the point of the squeezebox on forward. Is your squeezebox modded? or Stock? If not think about getting it modded. Enjoythemusic has an article about a cheap upgrade to the power supply as well as a list of modders. Next, your DAC - what kind of power cord are you using? Also think about getting the power supply modded. And so on for the rest of your system.
