From what I've read the transformer has as much if not more to do with the "tube" sound as do tubes. They're making audio tube amps these days without the output transformers. It's some three letter deal like OLM or something. From what I've read they are ultra clean but not as warm. The warmth comes from the transformer. Go figure. Has anyone played the Warwick amp that has a complete low wattage pre-poweramp with output transfor into the a switch mode power section?
I'm guessing, but I bet the Hellborg's output transformer is post feeback. Like taking a regular amp and adding a output transformer. So it is probably adding resistance and thus getting that damping factor/impedance curve going. And also limiting frequency response like transformers do. But with Hellborg listening in and guiding the ultimate signature sound.
Warwick definitely has the guts to try some innovations. This and their Tubepath amps. Good job Warwick!