The original Sony "Discman" D-50?
Sony spec:
20-20kHz +1/-3 dB
HD <0.0095% @1kHz
dynamic range >90dB @1kHz
channel separation >82dB @1kHz
output 1.6VRMS at MSB
headphone output 10mv per channel for 32 ohm load
no noise spec, no filter spec, D-5 spec slightly better