Hi Alan, well I also tried to find that DC adapter but thats much harder then to find this microusb 3Amp charger (for EU market I only found DC 3Amp on aliexpress so I didnt want to wait one month again). Tablet charges pretty good, when its ON I can say it can charge 20 percent in 30 minutes.
Here is the adapter I bought. http://datacomp.sk/qoltec-ac-adapter-15w-5v-3a-microusb-vhodny-pre-raspberry-pi-_d310126.html
Its in Slovak, but you can find similar based on the picture 🙂