More wire on the 26 pri, which could mean a bit darker.
a 24 = 15k dcr pri: 1430
a-26 = 30 k dcr pri: 2530
a-26 more collector value, used on 670 input.
a-25 will have less inductance due to dc handling core, which means less bass.
so
A24>A25 - less bass
A-24> A-26 - less highs
A-24> Jensen/Sowter/Lundahl - more everything, less "classic" sound.
just a paper guess, never actually prooved any of this conjecture.
differences will be minor.
there is no such thing as a bad transformer.
it's the people who abuse them that need to be put to sleep.
:razz: