I have a late 2012 Mac Mini 2.5 GHz Intel Core i5, and was just gifted a late 2014 Mac Mini 3 GHz i7. I have my CDs digitized to Apple Lossless and stored on an external hard drive and use itunes for playback. I have Boston computer speakers with a sub. I listen to most of my music with my computer, sometimes with headphones. I'm also planning on buying a pair of 300 ohm headphones- Sennheiser HD600.I think it sounds really good as is, but, I keep hearing that a dac will improve the sound. I would like to hear from Mac Mini owners what their opinion is. Is the improvement slight or very noticeable? Also, how much would it cost? Just any inexpensive $20 dac? All opinions appreciated.