A2DP Bluetooth receiver.
Be sure to get one that is at least BT 2.1 so as to ensure it properly supports higher fidelity audio.
This is the first device I tried (ordered from eBay).
This one worked. Audio was clear. No real issues. It fed my amps nicely. It has a rechargeable battery built in. It charges via USB. However, it does not function while it is charging. DOH! Listed as "Avantree Bluetooth Audio Transceiver"
So I ordered a different one.
Note this one is listed as: "New Bluetooth A2DP 3.5mm Stereo HiFi I-Wave Audio receiver Adapter Transmitter" although there is no "transmitter" functionality.
This unit is powered by USB. It "says" there is a battery option for it. I did not get this option. However, it really isn't required for my purposes.
This is the unit I am currently sticking with.
Pairing with the tablet was easy enough. So far so good. The audio quality is pretty good. I'm no audiophile and I'm sure it could be better, but it's clean and has good highs and lows. Makes my sub thump