Cafe Walter HA-1A in excellent shape. Runs off two 9-volt batteries, or AC power. Brand new power adapter included. These handmade amps have a bulletproof design and are the most transparent headphones amp I've found. No tone knobs to color the sound - you hear exactly what your bass sounds like. Includes an Aux in to practice with audio files, etc. Also has an Aux out. $200 shipped CONUS. From Walter's description: The HA-1A Headphone Practice Amplifier is a simple but high fidelity instrument amplifier, designed to allow you to practice your electric instrument through headphones. Unlike most music equipment, the HA-1A is not designed to make you sound good. Instead, it is designed to tell you the truth about how you sound. If your fingers make squeaky noises on the strings when you move, if your E string is twice as loud as your D, if your intonation is lousy - the HA-1A will tell you. And if you sound great, it'll tell you that, too. There are no tone controls, effects loop, enhance knobs, or subharmonic thingamajigs: the HA-1A tells you what you do sound like, not what you wish you sounded like. Your skills will improve because listening to the instrument in this way points out every little defect in your playing (warning - this may be painful). And your relationships will improve because your neighbors and family won't have to listen to those same defects, over and over and over and over again.