I suppose arguably, typical playback systems are potentially less limited in response up top than down below.
As soon as analogue equipment is in the chain the noise floor is often above dither noise floor levels(and it is not even noise shaped) and this is not usually deemed a problem. So discussing the limits of 24bit systems when your typical analogue floor is -85/-90dBFS is somewhat a limiting factor in itself.
It is rare a digital system is worth discussing in isolation as there has almost always been an analogue aspect involved.
Quoting from Manley Vari Mu manual :
Noise Floor -80 dB : 20Hz to 80Khz: -90 dB typical
P.S. In the name of not confusing a casual browser it might make sense if the twaddle from Mark G above was deleted, (amusing though it was)
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