Sync mp3s between 2 android devices? I've a galaxy and a Samsung tablet. I download many mp3s on the tablet and I'd like to be able to sync them with the phone and vice versa. Any app for this? 

I am talking about lots of files, so Dropbox and Google drive are not what I have in mind. The I'd like something that works over wifi
I recommend Google Music if it's available in your country. It allows you to sync 20.000 music files for free. Or even more if you pay.