My father, who recently passed away, was an avid audiophile and very proud of his stereo. I’ve been taking inventory of his gear, and while most things are easy to identify, I can’t find any distinguishing marks on this power amp. Can anyone help me identify it? The power tubes are 8417s. Thank you!Thanks again to everybody for all the advice. I will look into acquiring spare tubes and study how to power on safely with a variac. It's possible there's one among my father's things, as he was very fond of tube hi fi amps, as well as vintage guitar and bass amps. As for the schematics, I really appreciate that, but I read that there were multiple versions of the GSI mod, so I'll have to check to make sure that matches the circuit in the amp. It seems that Andy Fuchs, the guy behind GSI, is still building amps in New Jersey, so maybe I'll contact him with any problems.
Sadly I'm not at the old house that often, so I may not be able to hook up the amp or test it for a few months. I am looking forward to trying out the entire rig, though. Apart from the Dyna power amp, there's an Audio Research pre, a Linn turntable, and some homemade woofers that will be a pleasure to try out.