Presented herein are implantable medical devices, such as tissue-stimulating prostheses, that are configured to deliver simultaneous stimulation to a recipient. In one embodiment, a tissue stimulating prosthesis comprises a plurality of current sources, a plurality of electrodes (e.g., a linear array of electrodes), and a hardwired electrical network of switches, sometimes referred to herein as a “sparse switch network.” The sparse switch network is configured to connect each of the current sources to more than one of the electrodes, and to connect each of the electrodes to only a subset of the current sources. The sparse switch network is configured to prevent adjacent electrodes from being connected to the same current source.