Batch Convert Audio Files With iZotope RX

  You can batch convert audio files, including old ".sd2" files with the help of iZotope RX, including RX7 which I own.

 In RX7, select Window/Batch Processing. The batch processing window opens:

Drag and drop a dummy file in the "Input Files" section.

 Add a Processing step by clicking the + button. Select Apply: "Resample" from the list.

 Select With: Preset, or a custom settings to your choice. I chose 48k.

 Note that you can add as many Processing steps as you like, all the processing within RX are present: De-click, Normalize, etc. Save file as: your choice, I chose BWF. Set output options allows to select the destination, and the bitrate, I chose 24bit.

 Rename the batch process to your liking, I named it "Convert to BWF 48k 24bit". Now you can delete your dummy file from the list, the batch process is ready to use. You can create as many as you want and they will be listed there next time you open RX.

 Drag from the Finder to add the files you want to batch convert to the Input files section. Press Process! And let it rip!