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.