Cartridge impedance loading question

Hi folks. I have a Shelter 501 Mk 11 cartridge going into a Lehmann Black Cube phono pre. The Shelter's impedance is 12 ohms. The recommended load impedance in the Shelter specs is ambiguous…

Other than a user retrofittable option the Lehmann moving coil options are 80, 100, 470 & 47k ohms. What would you be using?

There should be no tonal change with different loads. If there is, it's either RFI or intermodulation from that high frequency oscillation. In such cases all you can do is load it down or try another cartridge or phono stage.
Pkoegz, When you mess around with very low output cartridges, there are many sources of noise besides RFI. If you hear noise, a careful investigation is in order to try to reduce it or eliminate it, but in some cases, especially with an all-tube phono stage, you may just have to live with a faint background hiss. I find this not to be annoying, since it is really only apparent when the stylus is up off the LP or during silent passages between cuts on an LP. In the situation you describe, I would advise leave well enough alone. There is no reason at all to fuss with the cartridge loading, and moreover, the loading will have only an incidental effect if any on "noise".
I think you miss understood, I have no noise. I was just wondering if that ment I did not need any loading. Since posting I heard from the engineer/designer of phono and sut. He confirmed based on the cartridge I was using, he would not "use any additional loading". I am a happy😺
And a cool cat, too.
Pkoegz, its a good idea to try the loading at least. If it improves the sound (reduces brightness without affecting speed or bandwidth) then it tells you that despite low noise, the preamp is sensitive to Radio Frequency Interference (RFI).

This interference is generated by the pickup itself, as explained previously. If you hear little or no difference, then its no worries- the designer of the preamp has done his homework.