Apparatus for communicating data between a transmitter device 16 and a first 51 and a second 52 receiver device, the receiver devices being connected, in use, to the transmitter device via a first 21 and a second 22 pair of wires respectively. Each receiver device is operable to receive signals detected as a change over time in the potential difference across the local ends of each respective pair of wires extending between the respective receiver device and the transmitter device, and the transmitter device is operable to transmit signals onto the wires at the transmitter ends thereof in order to transmit signals via a direct differential mode to each respective receiver via its respective pair of wires. The transmitter device is additionally operable to transmit signals to both receivers via a single common indirect channel and comprises: a channel estimator 1670, 1680, 1690 for estimating the extent of coupling between the common indirect channel and each of the receiver devices based on readings received by the transmitter device from the receiver devices; and a processor 1690 for determining a plurality of weighting values in dependence upon the estimated extents of the couplings; the transmitter 16 being operable to transmit a first signal via the direct differential mode over the first pair 21, to transmit a second signal via the direct differential mode over the second pair 22 and to transmit a combined signal onto the indirect channel, wherein the combined signal comprises a weighted sum of the first and second signals, the weighting being done in accordance with the determined weighting values; and wherein the transmitter further comprises a precoder 1640 for precoding the first, second and combined signals to pre-compensate them for the expected effects of cross-talk from the other ones of these signals, wherein the pre-coding of each signal, including the first and the second signals, is performed in dependence upon the determined weighting values.