The last two gigs I have experienced a strange situation with my - TopicsExpress

The last two gigs I have experienced a strange situation with my guitar rig; it manifests itself via clicking sound and complete lack of volume and power when I attempt to increase the volume. My rig consists of: Guitar --> Pod Pro v2 rack mount pre-amp --> (stereo/mono lineout) --> Crate Powerblock power amp (stereo/mono fx return) --> 2 8Ohm 2x12 marshall cabs. The Pod rack mount and the Crate Powerblock are in excellent condition, in fact I have spares of each and the situation occurs with all. So to explain the situation; I use a standard domestic 4-way reel and plug both the pre and power amp into it and proceed to crank the volume, this is when it seems the Powerblock appears to cut out and begin clicking almost as if its tripping? Yet, if I plug them into separate power sources, not on a 4-way, all is fine!! Now I have only tried a couple of different 4-ways but they react the same, and while I appreciate that most pub venues dont have the best electrics in the world, surely this shouldnt be a problem? Sockets are often a premium at many venues so I certainly need to resolve this soon. Has anyone got an advice or experience on such matters?