I need a better headphone amp

[mahatmakanejeeves]

1. Tube-anything is generally pricier than solid state-anything.

At least for hi-fi equipment. Old boat anchors, not so much.

Which tube headphone amp do you have? Is the schematic available on the internet?

Usually, defects in the tubes that do the signal processing do not cause hum. Hum, if it's pretty loud, originates in the power supply. Without further knowledge of what's going on, I'd immediately head for the filter capacitor in your power supply, assuming your amp has a linear power supply.

Vacuum tube hi fi equipment is about as easy a thing to fix as there is.

Please show us the schematic. Thanks.