On the PM-100 and PM-200, the LINE INPUT supports TS (mono, unbalanced) and TRS (stereo, unbalanced) cables. Balanced TRS connections are not supported.
If you are experiencing low sound levels when connecting a TRS cable to the PM-100/PM-200's V-DRUMS or LINE INPUT, please be sure that the connected audio device is not sending a balanced audio signal. You can also try switching to a TS cable—such as a guitar cable.