> The whole reason I went with tube was to get a silent amp...
It is generally a whole lot easier to make a tranny amp quiet than a tube amp. Especially with ICs.
I will assume your signal source is hum-free.
Noise (hiss): In all situations, a transistor can make less noise than a tube. The fundamental reason is that random noise is proportional to absolute temperature, and a tube's gain part (grid-cathode space) has to run 3 times hotter than a transistor just to work at all.
Hummmmm: In all situations, it is possible to reduce hum as low as you can afford. Just do what it takes. Good basic circuit that doesn't pass B+ ripple to the output (zero feedback plate-load triodes are excellent in many ways, but pass ripple right through). Good power supply filtering. Keep AC lines far away from signal circuits-- this may mean a larger case or even an external supply. Bringing the power switch to the front, past the amplifier and near the audio controls, is a classic problem.
Transistors again have an advantage. They typically use less power so power filtering is less expensive. Tubes work at higher power, higher impedance, and larger dimensions, so are more likely to pick up hum. Tubes can work low-hum with AC on the heaters, but when that isn't good enough (or you get bad tubes) you need a very large and quite clean (thus expensive) DC supply for the heaters.
Many small transistor amps work acceptably on batteries, which avoids all power-source hum. You sure can run tubes on batteries but you need a lot more of them.
-PRR
