A review of someone whom has build this amp too at DIYaudio.com
Great thread - I'll be following this with interest. I really appreciate the knowledge here, I've been lucky enough to have recently built three amps, an LM3875 chip amp with regulated 28V rails and a 6DJ8 based tube buffer, a Hypex NC400 Ncore set of monos, and the highlight of course was the Fetzilla. I would be hard pressed to sell the Fetzilla, it is such a good amp. The thing I like about it most is the lack of listening fatigue, it's got all the attributes I like, punchy bass, detail etc, but the gem is in the relaxed presentation. When comparing it against the Ncore for example, the Ncores can sound more dynamic, more detail, however ultimately the Fetzilla always snuck back and replaced them after a while. I really thought 50w (I used 120va) would not be enough to drive my 87db 8ohm speakers, especially as the trafo's were a little smaller than I would have liked and always intended to replace them with 160's at some point, but the specs don't always tell the whole story, the Fetzilla seemed to punch above its weight, that's how I would characterize it. I never tried driving it to party levels though.
I'm not smart enough to contribute along with others here on achieving higher power output, but all the same I will be interested in how it comes together and how the sound will compare with the original.
AJ