confusing subwoofer and head unit situa

I have a full alpine system in a 2003 Monte Carlo SS MRP-M850 mono amplifier 2x12 inch 1242d Type R subwoofers CDE-9870 head unit I installed them myself and have been having some issues. My subs hit but only a tenth of what they should be hitting at. While playing around with the settings on my head unit i found that if i turned off the Power IC (internal amplifier) my subs would hit to their full potential, but my speakers would turn off, as expected. I was just wondering if anyone had experienced anything like this or would know why this would happen. I've talked to a few people at some audio stores and they have pretty much said there is something wrong with my equipment, which i'm not willing to accept because its brand new stuff and works just not correctly. In my mind it seems like theres a setting that is limiting my subs from hitting to their full potential or limiting the frequencies that they are picking up when then internal amplifier is on but i am not sure how all of this stuff works. thanks, Dan

To rule out the possibility that you have a bad head unit you should measure the voltage on your subwoofer RCA coming from the amp. Put in a test tone, such as 60hz and put it on repeat, chose a volume on the headunit and keep it there. Get a digital multimeter and in the AC mode, touch the red lead to the center pin of the RCA and the black lead to the outside shield of the RCA, compare the average reading to the head unit internal amp being on and being off. If you get a way lower voltage reading from the head unit when the internal amp is turned on vs. being turned off, then there is going to be something wrong with that head unit. To my knowledge no settings change when you play with the internal amplifier on/off setting, it must be a issue with the headunit if thats the case. But if you get the same voltage reading on both, please report back.2003 Chevy Avalanche,Eclipse CD7000,Morel Elate 5,Adire Extremis,Alpine PDX-4.150, 15" TC-3000, 2 Alpine PDX-1.1000, 470Amp HO Alt.