1. A method for quantizing an input signal using a predictive delta-sigma modulator, comprising: generating error prediction values for a current block of input values based on a linear combination of error prediction values from one or more previous blocks, input values of one or more previous blocks, quantized values of one or more previous blocks and said current block of input values; computing speculative error prediction values for at least one input value in said current block, wherein said speculative error prediction values are computed for a plurality of possible quantizer output values; selecting one of said speculative error prediction values based on a quantized value from said current block; and subtracting said error prediction values for said current block from said corresponding current block of input values.