Quick update on battery issues on the nx507.
I turned off every android thing I could find that didn’t stop the streaming apps from working.
Screen usage since last full charge is 4 minutes.
I pressed play and came back every hour to see if the battery had moved like crazy. With 50% battery left it has been playing for about 3 hours and 10 minutes. If the battery drain is accurate, a bit over 6 hours is the max time.
This is, of course, not entirely standard usage. If I were listening that whole time I would have browsed music periodically. Probably to the tune of 30 minutes screen time. That very well may bring it down to that 5 hour number I was observing. 
I am not staying up late tonight. I will try and start the test earlier in the day so I can go to a dead battery. Maybe this battery was made by netscape and the last 10% will be near infinity?
I also got a new toy which may change the equation! So I am listening to something else while I run this test. 