Which is why I never recommend balanced. I don't know a single guy with a balanced dac who succeeded in optimizing his Lampi by trying different tubes. He stuck to what he has. Audioquattr ls an exception who religiously bought many for his balanced dac.
I know theoretically you might think keep everything balanced, but I also think a well done single ended Lampi is more nuanced without losing anything else including in a balanced system. Provided you have RCA inputs to pre, of course.
Jazzhead is running a single ended in a balanced system. It sounds so good he won't change to balanced. He has both the Koda 15 and the trinity pre, only the Koda allows single ended, and he had trinity dac, aqua formula, the top Stahltek dac and transport, neodio origine, and TAD CD player. He sold off everything and uses TAD as the transport to his GG 1 with KR 242 tubes.
I don't need balanced. It just happens to be the model that is being sold here...your analogy with analog rigs is a good one though.