Yes.
Connect the output jack of the external effects device to the INPUT jack (mono, high-impedance spec.), or connect from the PHONES/REC OUT jack (stereo mini) to the input jack of the external effects device.
- Use a stereo cable to connect from the PHONES/REC OUT jack to an external effects device.
Using a monaural Audio cable may remove the stereo effect, and shorten the time of use due to the increased current consumption.