1. A disk drive comprising: a disk; a head actuated over the disk; and control circuitry operable to: read data from the disk to generate a read signal; sample the read signal to generate signal samples; filter the signal samples with an equalizer filter to generate equalized samples; filter the equalized samples with a general noise whitening filter independent of any data pattern generated by a sequence detector to generate general noise whitened samples; filter the general noise-whitened samples with a bank of data dependent noise whitening filters to generate data dependent noise whitened samples; and detect a data sequence from the data dependent noise whitened samples.