Fidelity Research Headshell On SME Arm?

Which SME? If you have the FR headshell just try it.

I use a heavy head shell on a 3009/II for the same reason: add mass. It requires more weight at the back too, to balance. The added weight at both ends loads the knife-edge bearings down more firmly. The arm now plays low-compliance MCs beautifully. That was the knock on the 3009, back when MCs took over the 'high end': moving coils don't 'like' it. With these two simple mods, they like it fine. 

It's the M2-12R, which has an extra counterweight for this purpose. I would try it if I had one but I'm thinking of buying it because it's 20g and the only other 20g headshell isn't as nice looking. Asthetics matter!

Asthetics matter!

To me too — but ugly is OK if the music is great, I spend far less time looking than listening.

Which cartridge will you use, and why is extra mass needed?

It’s a Decca London Super Gold and it’ll only work with the SME if I add mass. Right now I have three quarters on the headshell (stuck on using blu tak) and it sounds lovely but it’s I can’t live with that forever!