What were the original power tubes?
Can't say I've ever swapped different types of power tubes before, but I've spent more than my fair share of time b rolling preamp tubes and I can 100% tell you there is definitely a difference in them. Mostly in the gain structure that comes up. But I can tell you that I've heard differences in different 12ax7's, 12at7's, and 12au7's. When comparing the same types of tubes, the differences were slight but there.
BUT.... I conducted the very scientific test of putting good headphones on my 7 yr old daughter and splicing recordings of two tubes together so they played the same parts seamlessly. You could tell when each was playing by a different color on the track (one teal and one blue). I told her, "tell me if the teal and blue are the same sound or if they're different. There's no right or wrong it's just what it sounds like to you." Two bars per tube. By midway through measure 7 she was saying, "the blue is better. The blue is better for sure. I like it more."
When I stopped it I asked her why she liked the blue one. Her response was CLASSIC. "They were the same but the blue one made me feel different. Like that's where the magic happens. It just made me feel better. I didn't know."
She has no musical training whatsoever but she picked out the Raytheon 12ax7 made in Japan from 1970something over the brand new JJ 12AX7. I honestly didn't think she would hear any difference, but there it was.