I have dozens of files which I need to export to M4A format (using win 8 and v. 2.0.5).
I have tried creating a new chain but exporting to M4A is not supported. I have searched for older beta versions which support it but cannot find anything available for download.
No - it’s a long-standing feature request which is long overdue to be implemented, in my opinion. I’ve recorded your “vote” for this which helps show us the “demand” for it.
If you must do it, I’ve got an unofficial build of 1.3.14 Beta that will export FFmpeg formats in a Chain, using the FFmpeg that I assume you are using for the outdated 2.0.5 version. If you want that build, I’ll e-mail you the link privately.
And also if you do need DSP effects you could try dBpoweramp. It’s trialware but most features except MP3 encoding are always free even after the trial.