Power electronic designers are interested in characterization of the magnetic cores permeability up to 10MHz and at high induction level. To achieve this aim, different experimental setups are used to measure mutual impedance spectra. First, impedance measurement methods are carried out on toroidal wound core of 20 μm nanocrystalline ribbons. Measurement uncertainties are estimated and a confidence factor is introduced as a useful consistency test to improve measurement reliability. Then a lumped equivalent circuit is identified to model electrostatic and magnetic frequency behavior of the device under test. It allows calculating complex permeability spectra over the resonance frequency of the device under test. Finally, we point out the limitation due to high excitation level. According to that, a flux-metric experimental setup is described and elliptical hysteresis-loops are measured. These results allow to consider magnetic linear behavior until a few 10mT and to extend complex permeability calculations to high induction level with good reliability.