1) The audio input may not be loud enough. If you’re using an auxiliary input, make sure that the volume on your source device (e.g. phone, tablet, etc.) is turned up all the way. 2) The headphones or speakers you’re using may not be able to handle a high volume. Try switching to a different pair of headphones or speakers to see if that makes a difference. 3) There may be something obstructing the sound path from the radio to your ears. This could be anything from dirt in the speaker grill to a loose connection somewhere along the way.