[ginger]

Occam,
The series capacitor and resistor idea is used routinely in the global feedback loop of most of the kit amps from these bods.
www.worldaudiodesign.com
That is they increase the feedback at low frequencies to improved damping. Its actually even cleverer than it first appears - if you do the phase shift analysis the phase shift is in the right direction to improve stability at low frequencies which is contrary to the usual idea that increasing feedback reduces stability.
Cheers,
Ginger

[Occam]

Ginger,

Thanks for the reference. The schematics seemed strangley familiar. It adds to my respect for Radford.....