well the hifonics amp usually detects what ohm load it needs, and i know if it's the Brutus line, it is stable at 1 ohm. what subs do u have? and is it going into protection right away? or is it after playing for a bit?
My Sony amp was bugging out like this too, it was being run at 4 ohms bridged (instructions say it's safe). It was either the wiring inside the box, or the fact that the box was wayyyy too small, as soon as I took the sub out of that box it worked perfect.
Or the fact that its a sony POS. My first Hifonics amp broke on my to. I have owned kicker, alpine, legacy, jensen, orion, and hifonics amps. The legacy, jensen, and hifonics all went up in smoke after a while. The kickers got water from a leak in my car in them while I was listening my system(it was raining) and they still worked fine. I have no clue how. The kickers never had a prob. The alpine was droped from 5 feet off a shelf, still worked. The orion, my most recent amp, has never had a prob. The jensen was rated at 400 watts and was running a pair of dayton 8's rated at 40rms. It over heated. So, the moral of the story..............if you don't buy POS's then your sh*t won't break.
Alot of my friends are using Sony amps, we know people who work at walmart that hook us up with them for dirtttt cheap and they get the job done. I just put a 1000w Sony into a friends integra, it's pushing two 10" Infinity's and they hit hard. I can only imagine what a ported box would do for them.
Im sure it's not pushing 1000w, you get what you pay for, but it works just fine.