Ask you to recharge is normal, but power off completely at 8% battery is abnormal.
Is this an one-off event or a repeated instance? If the problem is repeatable, we'll setup an investigation to check this out. Please record the state of the player when this happen again and PM me the detail,. Is the N6 playing a song when it power off? DSD or PCM? or is it idling? or Indexing Music library? We can try to replicate the situation by the state of the machine you provide and test our units at low battery condition.
I had a QLS-360 (charge/discharge like it should be), FIIO X5 2nd and no any issue with charging/discharging.
Today I discharged N6 to 0%, and start charging without using. So, now, after 5 hours and 17 mins my charger device upload a 5637mA. Controller should stop charging now, because an amperage dropdown to 0.1-0.15Ah, but it does not do it.
Look:
Ch. time - battery % - amperage - upload to battery
00:00 - 0% - 1.55A - 0mA
00:09 - 5% - 1.97A - 250mA
00:17 - 8% - 1.90A - 485mA
00:40 - 18% - 1.60A - 1173mA
01:08 - 31% - 1.56A - 1915mA
01:53 - 51% - 1.52A - 3059mA
02:33 - 68% - 1.44A - 4027mA
02:59 - 77% - 1.04A - 4559mA
03:25 - 84% - 0.72A - 4949mA
05:17 - 99% - 0.15A - 5637mA
05:38 - 99% - 0.13A - 5681mA
07:13 - 99% - 0.13A - 5890mA
08:01 - 99% - 0.13A - 5987mA
More than 8 hours and still have no 100%.
I have this situation with die at 8% (and at 10% second time) - twice. Every time I just listened a music in background, display was off, random mode. I use only FLAC files, most of all 16\44.1, sometimes 24\44.1. When I tried to power it on, it shows that battery is low and power off immediately. Then I can not power it on until charge.
Another user give me his charging log:
15:17 - 9% - 1,56A - begin charging (03:17 PM)
15:40 - 19% - 1,49A
16:00 - 25% - 1,45A
16:17 - 33% - 1,41A
17:17 - 53% - 1,35A
17:47 - 64% - 1,29A
18:19 - 74% - 1,22A
19:00 - 99% - 0,73A - 4900mAh
19:20 - 99% - 0,52A - 5128mAh
19:50 - 99% - 0,39A - 5310mAh
20:15 - 99% - 0,29A - 5467mAh
20:23 - 100% - 0,11A - 5503mAh
But mine charge on low amperage too long.
p.s. also I have an iPhone 5S and it discharge well for the first year, but then it can die at 8-15%. Then I went to the service and replace a battery. That is it.