dead amp or head unit?

If someone can please give me some direction to go with my situation. I have an Hifonics1206bxi amp. pushing a Alphasonik PSW815J sub and everything was going great for about 4 weeks unitl I decied to turn it up about 3/4 on the head unit and I smelled something electrical burning so I turned everything off and waited a few minutes. When I turned it back on, I am only getting about 1/3 the power. The amp never got hot and when I took the amp apart to inspect it for damage, there was none to be seen. The ground was good, the amp never went into protect mode. I have heard that Pioneer head units burn a lttile fuse out that groungs the RCA cables. If this sounds familiar or if someone can tell me what  to start replacing so I can get back to hearing the music. One more thing, the subwoofer is fine, impedence checked out just fine.jason3

If the fuse blows in the pioneer radio, you will not smell it.  When it does blow the usual result is engine noise.  I am not familiar with that amp in particular, but a lot of the Hifonics amps do have 2 seperate power supplies.  Some will still play with only 1/2 of each supply working.  You may not be able to see the damage.  Do you have an ohm meter?