A disk drive has multiple preamplifiers (preamps) connected to the system-on-a-chip (SOC) by a common transmission line with resistors between the preamps and the SOC. Each preamp includes a read resistor at the output of each read amplifier, and a write resistor at the input of each write driver. The resistors may be programmable resistors located in the preamps. The read resistors are at the source of the signal to the transmission line and the write resistors are at the termination of the signal from the transmission line. The read and write resistors provide impendence matching with the transmission line and the SOC when one of the preamps is selected as active, which enables the SOC to operate seamlessly with a common transmission line connected to all preamps.