The BOSS MA-15A is a compact amplifier with tone and volume controls. I have checked its operation. There are no problems. It's a BOSS monitor amp from about 30 years ago. There is no scratchiness in the volume or tone controls. Each jack is also problem-free. One of the tone knobs is missing. This monitor amp is made in Japan, so the materials are excellent. The output is 15 watts, so it can be used with any instrument. - Model: MA-15A - Brand: BOSS - Power: AC power - Controls: Tone, Volume, High/Low adjustment - Connections: AUX input, Line out, Headphone jack Thank you for viewing.