Both S-VHS and Hi8 retain the audio recording systems of their base formats; VHS HiFi Stereo outperforms Video8/Hi8 AFM, but remains restricted to high-end machines. In the late 1980s, digital (PCM) audio was introduced into some higher-grade models of Hi8 recorders. Hi8 PCM audio operates at a sampling rate of 32 kHz with 16-bit samples—higher fidelity than the monaural linear dubbing offered by VHS/S-VHS. PCM-capable Hi8 recorders can simultaneously record PCM stereo in addition to the legacy (analog AFM) stereo audio tracks.