An apparatus configured to couple to a plurality of subscriber lines comprising a plurality of transmitters configured to couple to a plurality of physical channels and at least one virtual channel. The number of physical channels equals the number of subscriber lines. A processor is configured to compute a precoder matrix to minimize an error value. The error value accounts for an error on each channel subject to a constraint on power for each channel. A precoder is coupled to the processor and configured to use the precoder matrix to jointly process a plurality of data signals to generate a plurality transmit signals for the plurality of physical channels and the at least one virtual channel.