Thank you for viewing. I tested it by connecting and playing for about 10 minutes before listing it. When adjusting the volume, gain, etc., there is some crackling. However, I've owned several headphone amplifiers in the past, and they all had similar issues, so I don't think this particular unit is necessarily bad. Batteries are not included. Please be aware of this. Alcohol-sterilized. Since this item has been handled by someone else, please refrain from bidding if you are looking for a perfect, brand-new condition. Shipping will be via Mercari's anonymous delivery service.