Meze Audio RAI PENTA Sound is normal, no volume difference between left and right channels, and no connector issues. There are absolutely no problems with its use. Headphones only. These earphones are prone to paint peeling, so please consider purchasing if you don't mind the surface condition. If you're curious about what kind of earphones these are, please take this opportunity to try them out. I think it's a masterpiece with a high degree of perfection among hybrid types, with a good balance from high to low frequencies. This is not a product that pursues resolution, but rather an earphone that allows you to feel the listening style that Mr. Meze aims for.