My band is live drums + A4, DSI Tempest, Moog Minitaur, OP-1, Minibute and a Roland 606. It’s all slaved to the A4 via midi and CV. Our drummer uses a Midi Solutions Beat Indicator…basically a very very bright blue light that flashes in clock divisions. It helps. When we played our first show we had to rig up a cardboard wedge to “point” the A4 at him so he could follow the Tempo light. That and decent monitors…you should be set. In my experience…unless you’re using the A$ strictly for atmosphere and keys, it’s worth it to clock your drummer to the A4.