Bad hum using Berning TF-12 with Beveridges?

I just purchased a Berning Tf-12 and hooked it up with my Beveridge 2sw's and there is a loud pervasive hum. To be fair this problem has happened with other preamps such as the Audio Valve eklipse, Precision Fidelity c7a. I bought the speakers with long Goertz ribbon interconnect hard wired from the Beveridge direct drive amps going to the input of the preamp. I wonder if I purchase shielded interconnects whether this problem might disappear. I know another Beveridge owner who happily used the Berning Tf-10 with his Beveridges.

Right now I am frustrated because listening though the hum is a chore but with the elimination of the hum the preamp would be marvelous! Even my wife commented on how good the preamp would sound without the hum. Any suggestions would be appreciated.