An interface device is configured to be attached to an audio device and at least one switch within a vehicle. The audio device recognizes a predetermined voltage signal as being a desired audio characteristic and then generates an audio signal having the desired audio characteristic. The interface device includes a central processing unit (CPU) and a wireless receiver. The wireless receiver may receive a wireless data signal from a wireless device corresponding to a desired change to the audio characteristic. The wireless data signal is converted to a first voltage signal. The first voltage signal is transmitted to the CPU. The CPU transforms the first voltage signal to an audio input signal, corresponding to the predetermined voltage signal recognizable by the audio device and corresponding to the desired change to the audio characteristic. The CPU may also receive a second voltage signal, which is converted to the audio input signal.