Shielded cable between pre and SET amp

Try moving your ICs around to a different location.

Are you sure the hum isn't in the amp itself due to power supply filtering/internal wiring/grounding?

I don't know the sound, but here:

https://www.partsconnexion.com/duelund-interconnect-cable.html

Two good responses so far.  IME, hum is typically grounding.  If it is shielding, then the Partsconnexion link Eric provided includes shielded selections.  Your other option would be to add a shield to your existing cables.  Purchase and add the appropriate sized tinned copper braid around your existing wires and connect the braid to the ground wire at the source end only.  Cover with Techflex and you are done.

Thanks! All great suggestions. Amp definitely not the source. I wasn't aware anyone made a shielded Duelund cable, but I may try to add a shield first just for the fun of the attempt.

Ok, update. The problem was the SUT that was sitting 2 feet from the preamp. Figured that was enough. Moved it 4 feet away, still noisy. Using the built in SUT now. Frankly it's hard to tell a difference. Problem solved!

Problem not solved!

The external SUT sounds so much better than the internal one that I'm just going to have to get some longer cables. 

I don't think it is a proximity issue with the external SUT, when I have used external SUT in the past I have always needed a shielded cable from the SUT to the phono stage or phono input on a preamp to avoid any hum.

What's a SUT?

I run a 45 SET with ICs that happened to be shielded, and I'm the process of building unshielded IC...hopefully I'm not heading into trouble.