burnedfingers wrote:
...Add on and route away from HT lines as to minimize interference....
Others may have a better idea of what might work :)
The magnetic field strength (as opposed to electric field strength) around a current carrying wire is proportional to the current it carries. If it is 50Hz-60Hz hum that you are concerned about, the heater wiring with its relatively high current is the one you want to separate your shielded input wiring from.
For example, the heater wiring to a pair of KT88 would carry 3200mA of AC current as opposed to the B+ wiring which might carry under 200mA of regulated DC current with minimal ripple. I would be more concerned about the heater wiring.
/b