Battery Powered
Battery-powered operation means the device can run from batteries.
This may use an internal rechargeable battery or a specified replaceable-battery arrangement. Battery support alone does not establish runtime, charging method or operation while charging.
Battery Powered — Headphone Amp
A battery-powered headphone amplifier can operate without a continuous mains connection, which can be useful with a portable source. Some models also offer external-power operation, with potentially different output or charging conditions.
Compare battery runtime under the intended load and output mode, and check how the battery is charged or replaced. A USB power input alone does not prove that an internal battery is fitted. Keep charging time and battery capacity separate from the simple availability of battery operation.
Battery Powered — MC Head Amp
For a phono head amp, battery operation powers the active amplification used before the following phono stage. The battery arrangement belongs to the head amp itself; it does not mean the turntable or the rest of the playback system is battery powered.
Compare the specified battery type, replacement or charging procedure and expected operating time. A unit powered only by an external supply should not be described as battery powered. Battery operation alone does not quantify the head amp’s noise or guarantee that every source of hum is removed.