Methods and apparatus for improving transmission channel efficiency are provided. In an example, a digital signal is received. A leading portion of a bit in the digital signal is pre-emphasized. The received digital signal is modulated with a pre-emphasis signal to pre-emphasize a leading portion of the bit in the digital signal. The pre-emphasis signal provides pre-emphasis substantially when a clock is high and the received digital signal transitions. The pre-emphasis signal does not provide pre-emphasis when the received digital signal is low or the received digital signal is unchanged. The pre-emphasized digital signal is then transmitted via the transmission channel. In an example, the received digital signal us a pulse-amplitude modulated multilevel signal.