It's possible to trigger audio files directly from an SD card in the TM-2. For these files to play properly, they must be in a specific format.
The TM-2 can play mono or stereo .WAV audio files that are 16-bit with a sample frequency of 44.1kHz.
Audio files that were purchased from an online music store such as Amazon or iTunes, or ripped from a CD, are usually MP3 or m4a audio files. These files cannot be played by the TM-2. You can use iTunes, Windows Media Player, Audacity, or other free programs available on the internet to convert these files to .WAV.
Refer to the program's documentation on how to perform this conversion.
If you're certain you have a 16-bit /44.1kHz .WAV file, and it still won't play, or you're getting an "Unsupported Format" message in the TM-2's display, then the file may have embedded metadata, or "tags," that are causing the error. This can happen with files that come from DAWs ("Digital Audio Workstations"), other audio programs, or sample libraries.
Metadata or tags must be removed from the file before they can be played in the TM-2. You can strip this extra information from the file by converting it to "Apple Lossless" or "FLAC" format. After removing the information, convert that file back to .WAV. Again, you can use various free programs to perform this conversion. "Audacity" is one of them.
iTunes can also be used: How To Convert Audio Files for Importing