Selecting the correct amplifier requires matching the signal gain (dB) and frequency range to the vehicle's head unit. For standard FM/AM, a gain of 10-20dB is usually sufficient; excessive gain can lead to signal distortion or 'noise floor' amplification. Ensure the device supports the specific frequency bands of your target market, such as 87.5-108 MHz for FM and 522-1620 KHz for AM. If the vehicle uses a digital system, prioritize amplifiers compatible with DAB/DAB+ signals to ensure future-proofing.