Hum problem with Alpha Goertz Sapphire cable - RCA type

I use Alpha Core Goertz Sapphire between pre and power amp (mono blocks). Both amps are tube. Cables are a couple of months old. One day I noticed a stronbg background hum in both channels. Today I called the manufacturer to help me solve the hum issue.
Their Technical Guru said "Buy another cable, i.e. if you get hum you can't get rid of it".
You guys out there are a lot smarter than that. I know it. The preamp is in arack. The amps are on the floor. The distance from the RCA to RCA plug is probable .8 m. Cable length is 1 m. What do I do to avoid the hum. Tape the cable to the rack. Play with the power cables? Please help. There must be a solution.
DC, i bought a pair of Goertz interconnects for a song for the very reason that you mention. The previous owner had a hum that he could never get rid of. He replace components, other cables, etc... and never suspected the Goertz. He finally tried some other ( balanced ) cables in their place and WHAMMO !!!, the problem was gone. He simply thought that the cables were "incompatible" with his components or that he was in a high RF area and was picking up noise. He thought that it was the balanced design that had cured his problem, not the fact that he had a defective cable.

As it turns out, i measured the cables when i first got them ( hey, i'm a tech by trade ). I found that one end had a resistive ( poor ) connection. Resoldered it and everything has been fine ever since. I contacted him to tell him about what i had found and that's when he relayed the above story to me.

To make a LONG story short, the Goertz cables need to be properly prepped when being manufactured. Quite possibly, someone was in a hurry and did not completely remove the insulation fully and soldered on top of it. You might have had a "resistive" connection that has become brittle or broken loose with flexing. I would have someone that is a VERY competent solderer touch up all of the connections inside the RCA's using a VERY hot solder station. A Weller with an 800* tip works fabulously.

Stereophile just used some of the Goertz cables for a review last month and commented that they were quite phenomenal in terms of resistance to RFI and outside interference. The reviewer lives very close to several high powered transmitters and specifically stated how clean and quiet there were with no signal applied. Don't give up hope without at least trying my suggestion first. Sean
I agree with the above listing. A poor solder connection can cause hum, but generally only on the amp that has the poor connection. Hum is also caused by ground loops. Power down and run a temporary insulated copper wire connecting the chassis of the power amps to the preamp chassis (metal to metal). If the hum disappears, you probably have a ground loop problem or possibly a high resistive return path on an RCA plug for the connecting cables. If the hum is present in both channels, and since your amps are monoblocks, I would suspect ground loop problems. Ground loop problems can be usually solved by tying the chassis of the affected equipment together, thereby placing the components at the same ground potential.
Thank you so much for info. I believe you guys are right.
Let me give some more info - The first pair of Sapphire that was shipped was so poorly assembled that one channel faded in and out. This is the second pair. Based on your experience I start to believe we have a quality of manufacturing issue with this manufaturer.
However, I do not think that is the issue now, since it is in both channels.
This is probably a ground loop.
Sorry for being a little non technical knowledgeable. Should I connect a regular copper wire from one of the scews on the cover of the preamp to the power amp ground terminal? I guess what I am asking is from where to where does a wire go? Can I use regular electric wire?
Thanks in advance.