Requesting help...fairly new to computer audio

I am about 6 months into researching, initial investment, and have ripped 11,000+ songs. I have tried to read most available (agon forums, CA, audio circle forums, WTC, etc) to self educate. I have settled upon ripping to apple lossless for a balance of sound and convenience. I dipped my toe in the water with an Arcam rDac using USB with macmini server. on some files it sounds great but on others harsh. The rest of my system is:
Bryston 4BSST amp
NAD M15 HD processor/preamp
New mac mini
B&W Nautilus 803's
B&W ASW 610

Does anybody have any suggestions about settings on the processor or mac mini as I have read about "MIDI adjustments? Room acoustics are not great.
What about an upgrade on the DAC...intrigued by the Wyred4Sound 2 dac. thnks