I connected my MP3 to the input of an amplifier, but it is playing very low, not providing full power. What should I do?"
Common amplifiers have high impedance inputs and normally require 200 mV to 1 V amplitude of the input signal to function normally. If the signal has a smaller amplitude, which occurs with the output of a device that uses headphones, the excitation does not occur. For the circuit to work, there are two alternatives. The first is to use a preamplifier that has a low input impedance and a high output impedance and the second is to use an impedance matching transformer as a small output transformer of the type used in transistor radios.
