If the sub is a dual voice coil, each @ 4 ohms, then you could wire it for a 2 ohm load or a 8ohm load. make sure your amp can run @ 2 ohms. And make sure your not going crazy with the gain. Generally dual 4 ohms would be used in a multiple sub configuration. ie , i have 2 subs which are dual 4 ohm voice coils. I have each setup to be a 2ohm driver, then I wired them in a series to get a 4 ohm load on my amp.
i know the amp is 2ohm stable, but im not sure if it is 2ohm stable while bridged. i suppose i could wire it at 8ohm instead so i dont put too much pressure on the amp? the gain is no more than a 1/3 of the way up, i made sure of that.
Yup, usually its only 4 ohm stable. If you run it at 8 ohms, it will be fine, you just won't get near the power.
BTW, I have the RF HX2's, and I believe the HE2's are 400 rms.
Thermal protection is just that. Protection from heat. Usually if the amp is going into thermal its clipping before it does. If your putting out 150 bridged as is, then at 8 ohms your looking at probably less then 100...way less, maybe less then 50. What amp ? Exact model please.
IMHO, maybe you could sell the sub and buy a lower power one. maybe a JL w0, or kick comp. something that takes about 100 watts rms. Try to match the speakers to the amps, underpowering a speaker is just as bad as too much, if not worse. Underpowering creates distortion which = not good for speakers.
For now, it would be better if you set the rear channels (I'm assuming you are just using the rear for the amp to be 3 channel) in mono, but hook one voice coil to the R and the other to the L. The rear channels MUST be in mono! That way you will get the most power you can to the sub while not killing anything in the process. Be glad you have an amp that is decent enough to let you know you are pushing it too hard :)
