AnyD-cells can provide such a wide amperage you want, but therange (the more the amps, the shorter the run-time) that it's not useful as a guide for sizing an AC adapter.
The equipment should state the amps required. Possibly on the inlet on the device, but definitely on the AC adapter which they sell for the purpose of feeding that inlet. You don't need to buy the adapter, just find a high enough resolution picture where the amps or watts figure can be read. Make sure to read the spec on the DC side. If you read the AC side watts by mistake, they will be a bit higher, and that won't really hurt your project - a few extra watts on the supply never hurts. However, if you read the AC side amps, it will understate amps by a factor of 10 or 20, and that would lead you to get much too small an adapter!