Interesting, as I can't see any correlation between RFI and a dedicated RADIAL (a spur comes off another circuit, so I'm assuming yours is a radial, or there's little point in installing one
). I've had fully dedicated (one radial per piece of kit into separate c.u. etc.) for over 16 years so RFI has never been a by-product of domestic ring mains interference. Having said that, cables can pick up some spurious wavelengths. My RFI was only on (moving coil) phono and diminished gradually from K boards to Prefix to Superline. Non-existent when I went to on-board valved phono stage or when I changed my record player (can't remember).
Oddly, when RFI was bad (and often in a foreign language), the s.q. was fantastic. Never did figure that one out !