The Bass Bump Headphone Amp is no exception ... The amplifier can be powered from either a 9V rechargeable battery, or a USB port. It’s a simple build, but definitely a good one to try on ...

9V batteries are often found in devices that aren’t used very often. If you use a NiCd rechargeable battery you may find it completely discharged by the time you need it. Capacitors on the other ...