Tube amps - what 3 things…

@hilde45 My experience as well. My PrimaLuna has been EXACTLY like owning a solid state amp with maintenance so far. None. I have had it 3 years with average amount of use. I haven't changed a tube yet. It sounds GREAT.  I would not want to mess with manual biasing. 

The ability to switch between modes (triode, ultralinear, pentode) is nice.

A fish with wheels and wings would be nice too.

Get a great sounding amp, not an overly complex spagheti bowl.

+1 on P2P wiring with silicone or other high temperature, NOT PVC, insulation. Tube amps require service and good designs can be made great with component upgrades and cct tweaks. One of my favorite amps was a Citation II reworked in the mid 80s. IMO, it ate my AR studio amps for lunch.

My God all this is so incredibly complicated. 

And after saying that, commentary herein is awfully impressive.

@atmasphere

Great synopsis 👍

The ability to switch between modes (triode, ultralinear, pentode) is nice.

I do not agree with this statement. The problem is that to do this properly, the output transformer (and the rest of the output circuit) has to be set up to handle the different operating points, and in practice this rarely happens.

If this is a concern, FWIW the original patent for ultralinear operation showed that the result had the same linearity of a triode with about 90% of the efficiency of a pentode output section. A lot of manufacturers realized the benefit, but to avoid paying the company that held the patent, moved the screen taps of the transformer to a slightly different spot, resulting in less linearity and simply called it good, thus bypassing the patent.

That patent has long since expired and the company that held it is unknown to most audiophiles and transformer manufacturers. As a result, its rare that the correct location of the screen tap on the winding is ever used. But if it were, ultralinear would be the only way to go if you are using an output transformer. Any competent transformer manufacturer could work this out though. Tradition of using the wrong position on the winding is literally the only thing stopping them!