I think JBL Flip 3 - http://www.jbl.com/bluetooth-speakers/JBL+FLIP+III.html could be a good option in this case as it has dual radiators for amplified sound output. Also it has Bluetooth as you require that. In addition this is one of the best weather proof speaker for using outdoor.
Link replaced by moderator.
Hope you will find this product useful.
I have a Lenovo Android tablet, and I have been using it to listen to music and podcasts. Its speaker is not great, and especially it is not loud, even when turned up all the way.
I went to a store and bought an inexpensive iHome bluetooth speaker for it, and when I got it home I found that the speaker didn't have any volume controls on it, and it was only as loud as the tablet's speaker, only with better sound quality. I took it back and exchanged it for a Jam speaker that had volume controls, but I found that with the tablet and bluetooth speaker turned up to full volume the sound was only as loud as sound played through the tablet's speaker.
I was hoping for a speaker with a built-in amplifier that would play music louder than the max volume of the tablet itself. I assume there are such speakers, but I don't know how to distinguish them from speakers like the ones I tried when I'm reading the descriptions. They all say things like "high quality sound that fills the room", but apparently that's only if the device the speaker is connected to can be turned up high enough.
Can you suggest any small, portable Bluetooth speakers that amplify the signal coming from a device so it is louder than the sound played through the device's internal speaker?