It looks like a pretty simple circuit (despite his annoying usage of blue blocks instead of the normal resistor symbols), so it shouldn't be hard to go through and at least perform some resistance-checks, which should at least tell you if the amp is safe to turn on. (If you don't have a digital multimeter, you're going to need one to test the Crack...there's a cheap & good one on Harbor Freight.) It might be instructive to go through and check the work to make sure everything's properly grounded and all.
I would NOT advise turning it on before doing some resistance checking, especially with Starky's story. I'm sure people in the DIY forum could help you figure out expected resistances. (I'd volunteer, but I'm a bit rusty and don't want people entrusting their lives to my physics skills.) I notice he doesn't give a resistance for the potentiometer (it's just labelled "Vol").
This amp is pretty similar the Crack (I don't have the Crack's schematic with me at the moment, but it's the same concept...you can even roll this one's 6AS7 and the Crack's 6080, since they're compatible tubes), so comparing the two could actually be quite interesting if you're so inclined.
Edited by aristos_achaion - 5/12/10 at 1:25pm