Hello hang-the-9 I am not sure that I understand your answer correctly. If you mean that I can just store the mp3 files on my smartphone, then select whichever I want to play using the Android file browser, then play it, then send the signal via bluetooth to the bluetooth speaker, yes of course !
My question is about finding a device that not only has the bluetooth speaker function, but also a mp3 reader function for audio files stored internally or on a SD card inserted into the device. I am looking for such a device and I want to be able to select the file to play through a folder / file selection dialog, and not just step to the next or previous mp3.
I have 10 GB of audio files, and I need to have them split into a hierarchy of folders for sorting purposes. I do not want to have these files on my smartphone, so I want to store them on a SD card of a bluetooth speaker that enables it.