You can do this in the Audio MIDI Setup built into recent editions of OSX:
1) Open up the Audio MIDI Setup application (located in the applications/utilities folder)
2) On the "audio devices" window that opens up you'll see a list of devices on the left and a little plus icon in the bottom left hand corner. Click the plus icon.
3) Click "Create multi-output device"
4) Add the different devices you need to this new device.
You're done, now you can send audio to this new device as if it were a single audio output.
You can change the name of the multi-output device if you want by double clicking on it.
You have to go into systems preferences and then select the output under 'sound'/'output', can also compensate for speakers being a bit out of synch by checking the 'drift correction' box in the audio midi set up window.
Tested and works with 2 bluetooth headsets (1 motorola and 1 Unotec WB Run)
source :
http://apple.stackexchange.com/ques...oth-speaker-and-headphone-jack-simultaneously