FLAC On A Mac


I know this topic appears here often but it seems to change every time I try to do a download.
I have a 7 year old MacBook Pro that i recently changed to OS to El Capitan after endless badgering from Apple to do so.  I previously had both XLD and Decibel on my OS for converting FLAC to Mac Compatible formats for the few downloads that I had ordered from HD Tracks.  
  I hadn't listenedto these downloads since the afore mentioned conversion.  i just ordered a new download (24 bit) from Presto Clasical and now I am getting messages that both programs will not work because they are from unknown developers.  Why these developers have become strangers to Apple after happily coexisting with them is another story but can someone tell me what the current best program for playing these files is>  My Internet search is unhelpful as everything seems to be recommending these two programs
mahler123

Spencer

  I probably wasn't clear before, but I did that, the XLD icon appeared, but when I dragged a flac file into the icon, the file bounces out and returns to it's own folder.  I didn't have that issue with XLD when I used it two years ago.

Check your settings in XLD PREFERENCES>GENERAL tab and make sure you have it set to AIFF. If it's set to FLAC, it will bounce because there would be nothing to convert going from FLAC to FLAC. Cheers,
Spencer
XLD works today without me having to do the above.
In the interim, I added a monitor to the system.  I have an Oppo 105 in the system but it was for audio only.  With the monitor added I can now play flac files from it's usb inputs, so now I don't think that I want to go through the hassle of converting the flac files to AIFF.
   However if I change my mind, the Oppo will play WAV, not AIFF.
If I am going to convert the files to a mac format I might as well pick
a codec that will also play on the Oppo.  What program should I use?  I've heard good things about JRiver


"Oppo will play WAV, not AIFF." That is not correct. I owned an Oppo 105 and 105D and both play AIFF fine. I did this using the digital inputs on both the front and the back with no issues. Seen many other Oppo owners do the same.  

What do you mean by "monitor"? Hardware, software? The only monitor I know of is a pair of small speakers used in a studio.

For mac music software, Audirvana+, Amarra & Pure Music are the top ones. You can trial them all & decide for yourself. JRiver was made for Windows, and just recently released for Mac to mixed reviews. I haven't heard it so no opinion. Cheers,
Spencer