Balanced OUT Transformer specs. question

[Marek]

Hello again! :-)

Here's a question to you, guys:

What are the (approx.) specs. of the 'balanced out' transformer which one can find in many amps?
(what is (approx.) input impedance and what is the output impedance?)

Are these any good for this application:

http://www.neutrik.com/content/products/products_entry.asp?productid=210_74481&sublevelid=204_174211
http://www.neutrik.com/content/products/products_entry.asp?productid=210_134581&sublevelid=204_174211
http://www.neutrik.com/content/products/products_entry.asp?productid=210_252001&sublevelid=204_174211

Thanks in advance!

Marek