Although you should be able to, would not recommend it (with following caveat). The wall outlet USB ports typically range between around 4.5 and 6 amps, whereas the USB power adapters typically range between 1 and 2 amps. (The amp rating is basically a limiter/governor--limits the current of the charging power from the source). The power adapter itself is basically a transformer (5volts, 1amp).
As with anything electrical, using higher amperage than originally designed/recommended is usually not a good idea. If something malfunctions, the lower amperage is there to protect the device. (and anything nearby). These USB combined outlets are really designed with fast-charging cell phones and tablets in mind. The outlet USB will only provide as much power as needed by device when working properly. It is when something malfunctions that an issue occurs and all bets are out the window. Not too bad if you just have to replace a $40 device, but if the TV melts and the drapes catch on fire, well...
Of note, the manufacturers of the most common USB charging outlets don't mention the use of streaming devices on their spec sheets and compatibility. With that in mind, I would err on the side of caution and limit my devices to 2 Amp maximum power adapters.
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