Hi! Yesterday, I bought a used Ashdown ABM500 at a really good price! It sounds like expected, BUT when I engage the compressor, the volume drops really low. Even when I have the knob full counter clockwise (7 o'clock) the output is really low with no compressor effect. When I turn the knob it gives me more compressor effect but still at a low volume. Anyone else has this problem? Should it be like this? If not, anyones got a hint of how the problem can be solved? Here's a sound sample. The middle part is with the compressor engaged and the knob at zero, 7 o'clock.