This paper considers the multi-channel gain margin problem for linear time-invariant continuous-time multi-input multi-output plants controlled by memoryless generalized sampled-data hold functions (GSHF). It is proved that arbitrarily large output gain margins can be achieved by suitable selection of the sampling time and the hold function. We use state space methods and give a constructive design procedure. The controller we use is memoryless in the sense that the discrete-time closed-loop system has the same McMillan degree as the open-loop continuous-time plant.