You might try the 15dB circuit and see if it is more to your liking, and you can always manipulate the values of R1, R2 and C1. But I personally wouldn't want to use much bypass capacitance with higher-value attenuators. Once you get past 10dB or so, I don't like bypassing as much of the attenuation in the top octave with PSD2002's, because they already have pretty strong output above 10kHz.