OK, so I converted the FLAC files to AIFF using Amarra HiFi, they play fine now. I also downloaded the trial version of Audirvarna Plus, so I could play the FLAC files directly without using iTunes. Comparing the regular CD version of Norah Jones "Come Away With Me" with the AIFF (via Amarra HiFi) and FLAC file (via Audirvarna Plus); both HD audio files were immediately far superior to the regular CD; no two ways about this! However, the difference between AIFF and FLAC was much more subtle. Both my wife and I preferred the FLAC file, slightly more dynamic and cleaner sounding. Although I have to admit, the difference was more like preferring one shade of yellow to another, a lot more subjective. At the end of the day I have decided to stick with FLAC, via Audirvana Plus; partly to avoid the hassle of file conversion and my preference for the sound of the FLAC file over AIFF file sound.
Overall, I am extremely happy with my first foray into computer audio, it has given me a new love for our hobby.
Overall, I am extremely happy with my first foray into computer audio, it has given me a new love for our hobby.