My main use of Android MP3 files is to listen to podcasts. My workflow is as follows:
Use Google Reader to subscribe to and browse podcast feeds. The MP3 files are linked in each feed, so the ones I decide to listen to get downloaded to my computer. I use DownThemAll for downloading, because it's good at this kind of download and because it preserves modification times on files it downloads. However, I'm moving away from Firefox, so I'm now looking for a similar plugin for Chrome.
Periodically plug my phone into a USB port on my computer (use USB3 if you have it, absurdly fast), causing the SD card to be mounted as a removable disk. There's a directory,
listen that contains all my podcasts.
Since I listen to them in the order of the modification times, I sort the directory listing by mod times and delete all the ones I've listened to.
I move all of my new downloaded files into the
listen directory on my phone.
I tell Windows Explorer to "eject" the removable drive (this ensures that all file writes are completed) and unplug the phone.
I plug in my headphones and run MortPlayer Audio Books. Although not specifically designed for my use case, it has some features I need:
- The ability to be pointed at any directory I want.
- The ability to automatically sort my files by modification time.
- The ability to automatically remember where I left off.
Obviously, the way I listen to MP3 files is different from the way most other people do, so you'll need to figure out your own workflow. In particular, you'll probably want a different audio player program. But judging from your prescribed needs, you want one that lets you just copy files directly into an SDCARD directory. Most do.
Ideally, one could use Bluetooth to copy files. I've tried that, but have found that Bluetooth copying software is slow, a pain to use, and doesn't preserve file mod times.