Same as in Fig. 5 but for the PSD amplitude. The black, red, and brown points in the upper panel show the LF best-fit log(PSD_amp) values plotted as a function of L_X for AGN in the B′, C′, and D′ boxes in Fig. 6. The bottom panel shows all the LF and FR PSD amplitudes (listed in Table 2) plotted as a function of M_BH (black and red points, respectively). The dashed lines indicate the respective mean PSD amplitudes.