Triode or Ultralinear

Learsfool, you might also include push-pull triode amps in your quest; not all that is triode is SET.

I'd just like to add that what you're doing by flipping the switch is only a very vague comparison of the general characteristics of a Triode-based amplifier, and an Ultralinear output circuit. What you're REALLY comparing is your Primaluna amplifier with the output tubes' screen grids connected in two different ways.

Changing this connection affects a bunch of circuit parameters simultaneously, including its static linearity, transconductance, plate resistance, grid-to-grid capacitance, output transformer HF damping, etc. etc. . . . all of which will interact with the manner in which the global negative feedback loop (if applicable) behaves. And since it's really impossible to get all of these parameters perfectly optimized for both modes, some of the differences you hear in the sound are going to be due to side-effects from switching between each mode, rather than necessarily from their generic differences.

So IMO you can freely decide which one you enjoy more, independently of any preconceived biases about Triode/Ultralinear circuits in general . . . and your experience with this switch on the Primaluna may or may not have any correlation with what you prefer on other amplifiers.

for what its worth......it seems like my sub consistently sounds (integrates) much better in Ultralinear mode. In Triode mode it is kinda hit or miss with the sub.