Question about Jensen input transformers

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Hi, guys.
I've been toying with the idea of designing a fully balanced tube mic preamp with a transformer input stage. I have seen the schematics on the Jensen website:

http://www.jensentransformers.com/as/as047.pdf (Two JT-115K-E used in symmetrical mic input stage)
What I don't understand is why you couldn't use a single input transformer and couple the two outputs to each of the two grids of a differential pair of tubes? The second Jensen schematic shows *two* transformers, one for each tube in a differential pair. Why?
My only suspicion is that the transformer outputs to the grids need to be ground referenced, but that could be taken care of by using 1% matched resistors to ground on each line, right? I've seen it done on non center tapped heater windings of power transformers, why not on input transformers?
Is it simply a case of Jensen wanting to sell twice the # of transformers?
Thanks for any insights you might have.
Sincerely,
-Erik.

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Topic - Question about Jensen input transformers - e.lectronick 09:03:16 01/24/01 (1)

Check with the Bottleheads.. - RBP 12:31:14 01/26/01 (0)

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