When I went to look for the link, I saw that he had a new website. I thought he had published more specs previously, and I even remember thinking he might have provided too much info, as someone could build their own from it. It's not there now. There is some more info at:
http://www.steve1mac.blogspot.com/There's a photo of the innards, a frequency response chart, but nothing regarding phase or the levels it can handle. At the price point and seeing the photo, I doubt that the transformers are stellar. But I've had a lot of luck using them with intercom connections where fidelity is not usually a topic, and I thought they might be worth adding to anyone's kit. I would use them for straight audio in a pinch, but then I have a pair of two-channel Radials for the critical paths to go to first.
It's my understanding that using two transformers makes it work for intercom, but I have to wonder if they're well matched enough to provide balanced audio that's, well, balanced.
And of course I have no connection other than being a satisfied customer.