Sony - WM-D6C Walkman

Main Features Dolby B and C NR: It was the first Walkman to include Dolby C noise reduction (in addition to Dolby B), drastically reducing the natural hiss of cassette tapes.
Laser Amorphous Recording Head: Equipped with a high-quality read/write head, extremely durable and capable of capturing an extended frequency response.
Quartz Speed Control: Ensures the tape runs at the exact speed of 4.76 cm/s, eliminating audio fluctuations (the so-called wow and flutter). It also has manual Pitch Control adjustment.
Tape Compatibility: Supports all types of tape (Type I - Normal, Type II - CrO2, and Type IV - Metal), for both playback and recording.
Professional Connectivity: Includes dedicated inputs for microphone, Line In and Line Out, which made it a preferred tool for journalists and sound engineers.
The Current Market and Collectibility Value
Today, the Sony WM-D6C is a highly coveted collectible item and a milestone of vintage culture. Units in good working order or fully restored fetch fairly high resale values on specialized platforms.