5kHz is still only the higher end of mid-range. I wonder why they added a hardware filter.
Maybe the small amount of analogue circuitry to provide the line out isn't too good with it,
or maybe they assumed smaller speakers in TVs and monitors, and didn't want to send them
the higher frequencies that would only serve to distort those speakers.
I find it interesting that depending on where the low end cuts off,
the entire frequency range could fall within the range of a vintage tube amplifier.
Might have to try that.