When I connect a turntable to my B2, why is the volume extremely low?

Some turntables may not have a built-in preamp and you would need to add an external phono preamp to bring the instrument level signal of the turntable to line-level. Some turntables may have a built-in preamp but have a switch on the back for either "line" or "phono," such as the Music Hall USB-1 or the Audio Technica AT-LP120; the switch would need to be selected to "line" in order to work directly with the speakers.