dB indicator flashing red

[f1eng]

It is the clipping indicator. I think it may flash at 1 bit below full modulation.The track you were playing was probably one of the (appalling badly recorded IMHO) modern tracks where the signal is hammering up against the limiter.
Worth looking at the level meter page on the display and see if it is getting to clipping.
I do not consider any recording which spends much time "in the red" to be much good SQ wise, personally.
HiFi it ain't.

Do you mean input clipping?  I'm surprised that ethernet AIR would pass a signal to the amp that would cause clipping?  The level meter on the louder passages of that track is permanently in the red.

I certainly agree with your comments about the bad mastering of many modern recordings.

I think Air just sends the file it is given. If the file has full modulation on it it will be sent and the orange indication will flash.
If your volume control is below 0dB I can not think of any other explanation.
Does the indicator flash on the app as well as the main display? If it does I will look at mine when playing some of my most loudness pushed recordings to see if I get it too. I can't see the main display from my listening chair.