Comparison of the recovered source-plane results with respect to the input model, for D|$_{\rm 2}$| (source  = |$s_{\rm 1}$|⁠, |$P_\mathrm{ f}$| = 3 per cent, i = 90 deg; top) and D|$_{\rm 7}$| (source = |$s_{\rm 2}$|⁠, |$P_\mathrm{ f}$| = 12 deg, i = 45 deg; bottom) at 2 and 3 GHz, as an example (note that we simultaneously model all channels). The rows contain the Stokes |${\boldsymbol {I}}$| (top), the polarization fraction (middle), and the polarization angle (in deg; bottom) for both data sets. For clarity, we mask the colour maps to include only the region of the highest SNR, where the input surface brightness Stokes |${\boldsymbol {I}}$| is at least 20 per cent of the peak. The residual RMS values are computed within the same mask.