These guys were a big help to me:
You will need a DAC for decent sound quality. Start with something less expensive like a Concero or metrum octave. Drive it with a good USB cable like an audioquest diamond or coffee. USB cable should be 1.5-9 feet long, no shorter or longer.
Start with a good playback software on the Mac, like Audirvana or Fidelio. Some are free. Rip your CDs to wav or ALAC format using free software tool XLD:
The most important first decision to make is what kind of format you wish to store your digital music. The best quality is "lossless" vs "lossy" (like MP3s). That could be WAV files, ALAC files, or FLAC. ALAC is proprietary to Apple, which would pose problems should you go with another operating system. WAVs purport to have higher quality, but you forgo the metadata that you get with FLAC or ALAC (ie the artist name, track name, album name, etc.).