Metal ion beams are more and more requested by physicists (Nuclear Physics, Material Physics) for their experiments. At GANIL, they are produced by Electron Cyclotron Resonance (ECR) Ion Sources for the two accelerator machines: ECR4 & ECR4M (Sortais et al., 1989) [1] for the Cyclotrons and PhoenixV3 for the Linac (Thuillier et al., 2016) [2]. One of the challenges is to produce these beams with high global efficiency: today, total ionization efficiency varies between $\sim$1% and $\sim$28% regarding the method carried out. A new alternative would be the 1＋/N＋ method studied intensively for the past twenty years in the framework of Radioactive Ion Beam (RIB) production. In this article, the primary results leading to the proof of principle of that technique applied to the production of metal ion beams is presented.