iTunes absolutely handles high res playback. It is the DAC and the interface to the DAC that limit how high resolution you can play.
If you are talking about FLAC files downloaded from HDtracks, that is true, iTunes doesn't play FLAC. But you can convert FLAC to AIFF or to Apple Lossless and iTunes can play them without problem.
Having said that, many third party players do sound better than iTunes. I have tried Amara and have used Pure Music for a few years. My current favor is the Audirvana Plus because it sounds best to me and its iTunes integration is the most reliable.
If you are talking about FLAC files downloaded from HDtracks, that is true, iTunes doesn't play FLAC. But you can convert FLAC to AIFF or to Apple Lossless and iTunes can play them without problem.
Having said that, many third party players do sound better than iTunes. I have tried Amara and have used Pure Music for a few years. My current favor is the Audirvana Plus because it sounds best to me and its iTunes integration is the most reliable.