Can I use a guitar cable with my lavalier/headmic transmitter?
No. The output impedance and levels between these types of microphones and a guitar transmitter are not the same. There are also different components in the input circuitry of the transmitters to accommodate the type of input intended (including phantom power for the condenser mic elements). Only use transmitters set up for lavalier and headmic with those type microphone inputs exclusively. Instrument transmitters are different and specifically designed for guitar and bass signals.