DENON DAP-5500 May 1987

A4 sheet folded once, on the DAP-5500 - DENON calls it the world’s first digital pre-amplifier (¥200,000). The idea is fanatical: the digital and analog sections are split across two separate chassis right down to their power cords, coupled only through fast Hewlett-Packard opto-isolators. At the core is a 4DA push-pull super linear converter (four DACs per channel, patent pending at the time) with a C.A.L.P. filter and 4x oversampling, fed by an optical DIGITAL-1 and coaxial DIGITAL-2/3 inputs that auto-detect 32/44.1/48 kHz, with a non-feedback FET UGI amplifier at 1 Ω output meant to drive the power amp directly. The back cover pairs it with the DCD-3300 CD player (also ¥200,000).