Every mains powered product is subject to tiny amounts of leakage of electricity from the mains.
These can cause very mild electric shocks.
It is a sign that the whole system is “floating”, meaning without any earth/ground connection.
In this case, it is necessary to add a supplementary earth/ground to the system. You should consider our GroundHog+ device.
The Pro iCAN/Pro iCAN Signature is designed to operate without requiring an earth/ground connection for electrical safety, however for best audio quality and to avoid these mild shocks an earth/ground connection for the system is required.