I wouldn't call it subtle, as far as i can tell it i mounted all the parts correctly, too.
I took some pics of the wiring, if those help
OT wiring looks weird on the pics, but it is correct (for 8 ohm, i wired it for 4 ohm first and re-wired after i noticed)
http://imgur.com/a/jqLBn
edit: the drain wire from the shielded cable going to H1U is not soldered (it doesn't seem to say to solder it, just attach, i just checked again), but in later pictures it appears to be soldered.
Could that be the problem?
edit2: it wasn't