funny thing ohms!!!!

hey guys got a quick question, i talked a guy into swapping me an power hx2 10 for a alpine s 12 because he doesn't have the power to even move the sub. well i built the box and wired to sub to 2 ohm load, worked fine on my amp but it cuts his amp off with the 12 but not with 10. the 10 is a 2 ohm sub and the 12 is a 4 ohm, i was wondering could it be the jumpers that alpine use on there subs that is cause the sub to turn the amp off? sum help would be good guys thanks for your time.

Was he using the 10 at 2 or 4 ohms?

What amp does he have?

If it's a 2 channel, it might not be stable into 2 ohm mono.

he has it on a cheap ass sony 4 channel amp is there a way so i could wire it to a 4 ohm load so it could run okay in his setup for right now until he gets a better amp
and i think the 10 was wired down to 4 don't really know for sure my buddy and i built this thing years ago don't even remeber