A two-stage sampling data detector for a partial response channel having a channel code encoder for encoding user information sequences into blocks of code words in accordance with a predetermined channel block code characterized by a list of most likely error-events comprising impermissible code words. The detector includes a first-stage detector, such as a Viterbi detector, connected to receive samples from the partial response channel and matched to characteristics of the channel and not to the channel code, puts out unchecked bit estimates. A second stage post-processor checks the bit estimates in relation to derived detector decision metrics information and the channel block code, and puts out post-processed bit estimates to a channel code decoder after correcting detected erroneous sequences in accordance with the decision metrics information, information derived from the channel code, and the list of most likely error-events. A method for generating the channel block code is also described.