With the 4-cable method, a multi-effects device is connected to a guitar amplifier using a total of 4 cables. The prerequisite is that both the amplifier and the multi-effects device have an effects loop-in path (FX loop) that can be recognized by the jack sockets labeled "SEND" and "RETURN".

With the 4-cable method, the guitar is connected to the input (INPUT) of the effects device (cable 1). Here the signal goes through so-called pre-effects, i.e. effects that are usually placed in front of the amplifier, such as compressor, overdrive/distortion or wah.

From there, the signal is outputted via the SEND socket of the effects device and sent via cable 2 to the guitar input of the amplifier (INPUT). It goes through the pre-stage of the amp and is tapped with cable 3 at the SEND of the amplifier in order to be fed back via the RETURN of the effects device.

Then the so-called loop effects (e.g. modulation effects, reverb, delay) are run through in the effects device before the signal is sent via cable 4 from the OUTPUT of the multi-effects to the RETURN socket of the amp. The output stage of the amplifier is then controlled from there.