Texting file size limits for attachments is relatively small. MMS is limited to either 300 KB or 600KB. A lot of the third-party texting services allow bigger files, for example WhatsApp allows up to 16 MB but that's as long as both sender and recipient are using the WhatsApp app. So depending on what texting app and service you're using, unless everyone you're exchanging music files with is using the same service, you've got to be selective when you use SMS/MMS to exchange files. A lot of services even scale down high res images/vids if they're too big. You'd be better off using email or the file sharing capabilities of a service like Dropbox for larger files.