Looking for audio device with specific features

[Climbo]

Hello everyone,

I have a "party PA speaker" that unfortunately lacks a USB in for MP3 playback...

I'm looking for a portable device that:

1. can be powered through 5V usb
2. Has a line out (headphone) plug
3. that can play MP3 by attaching a USB key
4... and that is where my headache starts: can play those MP3 from point 3 randomly... and not just sequential order

many portable Bluetooth radios has 1 to 3... but I need 4 as well....

Any suggestions?