I don't think Electra-print makes parallel feed iron, let alone nickel core specimens. You will want to contact Mike at Magnequest, or Dave Slagle to get the iron specified in the article.
Many of these special nickel transformers will not have tapped or reconfigurable secondaries, so you will need a good understanding of how much noise floor is acceptable for your particular headphones. When you combine this with the lack of DC heaters on the 45, the circuit looks a lot less appealing for headphones.
Still, if you plunk down for good iron, design a decent DC heating circuit, and use a lot of step-down in the output section, this could make a lovely headphone amp!
I will make a shameless plug here for our Stereomour 2. We have altered the original Stereomour to allow us to implement DC heating, and of course our output transformers can be set all the way down to 2 Ohms for extra low noise. The shunt regulated power supply upgrade that we will roll out is a feature seen in later Tucker designs (with some slight differences).
