The results of the “Kovdor-2023” experiment on deep electromagnetic sounding of the Earth’s crust within the Archean basement of the southwest of the Kola Region with natural (magnetotelluric sounding, MTS) and artificial (controlled source audio magnetotelluric sounding, CSAMT) sources are presented. The experiment was intended to study the electrical conductivity of the upper Earth’s crust in the area of the Belomorian Block of the Fennoscandian Shield in continuation of the work of 1995, as well as the “Kovdor-2015” experiment, which suggested that the presence of a heterogeneous conductive layer (DD layer) with longitudinal conductivity from tenths to units of siemens in the upper part of the Precambrian crystalline crust at depths of up to ten kilometers is an inherent regional characteristic of the Fennoscandian Shield. During the 2023 experiment, technologically improved versions of field generating and measuring equipment and the new data processing methods were used. The earlier studies have identified the need for the modified measuring equipment with the frequency range expanded towards high frequencies, as well as for better synchronization between the source and receiver. Thus, to carry out the experiment, a new generator group and a new electronic unit combining functions of the control unit for the generator and the source output recorder, as well as a technique for synchronous processing of time series of current in the source and the electromagnetic field component at the observation point, were developed. The “Kovdor-2023” experiment was carried out using a new generator and a new measuring system, which made it possible to obtain additional information about the upper part of the object studied. Synchronous processing of new data was carried out, taking into account the materials and experience of the previous experiment, including static distortions and displacement currents. MTS and CSAMT data were used to construct a geoelectric section using the MARE2DEM program.