Hum.....??

I finally got around to connecting a set of Kimber Hero's to the tt last night. I had neck surgery about 6 weeks ago and wasn't allowed to lift much of anything. These cables were a very tight fit on the SME arm. Anyway, now I have hum in both channels. I'm presuming the Hero's are not fully shielded and therefore not suitable for a phono ic.

Is this correct?