SRS off light on while driving

If it is lit up for "off" this could mean that either there is something in the passenger seat that is similar to the weight of a small child, the passenger seat cushion sensor is faulty, the system needs to be recalibrated, or there is a fault of some other kind with the system. Other than ensuring that the passenger seat is clear, all other testing will need to be done with a scan tool that has the capability to read codes, parameters, and recalibrate the zero point setting.

I forgot to mention that the seat is unoccupied with the exception for a couple of items placed there weighting no more than 6 ounces. Also, under the seat is an audio amplifier mounted to the floor - could that be causing a conflict with the SRS?

Only if it is contacting something under there or the wiring is tampered with.