A soft decision value output detector includes a plurality of maximum a posteriori (MAP) detectors. The MAP detectors are connected in parallel, and configured to simultaneously generate state metrics for portions of a sampled data sequence, and to generate soft decision values based on the generated state metrics. The MAP detectors may generate soft decision values in a fixed latency manner and without buffering the sampled data sequence for a whole sector of a disk in a disk drive. The MAP detectors may generate soft decision values for portions of the sampled data sequence at least at a rate at which the portions of the sampled data sequence are input to the MAP detectors.