In this paper, we report the experimental demonstration of 320 Gb/s demultiplexing to eight simultaneous always-on 40 Gb/s tributaries with near-zero latency. The single-channel, single-polarization 320 Gb/s optical-time-division-multiplexed signal was processed by a copy-and-sample-all architecture. 1-to-8wavelength multicasting over more than 10 THz of bandwidth was achieved in a self-seeded two-pump parametric amplifier, and was followed by a single gate, multicolored sampling with equalized response over more than 20 THz. The single gate operation allows for truly scalable real-time processing while avoiding the complexity of parallel pipelines processing. Error-free performance was measured over all extracted 40 Gb/s tributaries with less than 4 dB power penalty compared to conventional single tributary gating.