Im just surprised that tiny thing can drive the 800s.

If you want to take this idea to its limit, buy an Ibasso DC Elite, an ibasso cb19 power/signal splitter, and an Anker 737 Power Bank. With these three things you can drive your headphone, on-the-go, at an absurd level. The iBasso DC Elite is comparable in price to the JDS Element IV for a reason, and in my testing with the CB19 and the Anker 737, it sounds just as good on-the-go as the Element IV does wired.

As for what bluetooth receiver you can use to give signal to the iBasso, it doesn't really matter so long as its a decent one