2/3 crossover with stock head unit

Hello I am in a bind with my stereo problem and for the life of me I cannot figure this out.

Currently I am running a Visonik 210 bass system with the included amp, but on my truck I just bought I only have a stock gm head unit. (1997 Chevy Tahoe LS)

So i bought a ssl 2/3 way crossover and I took a signal directly from the speaker wires coming out from the head unit and put it on the crossover's rear input section, then I put my amp on the sub out section of the crossover. But it clipps my sub Hard!, I have to set the gain on the amp way down past half way and turn the sub level setting on the crossover all the way down to keep it from clipping and majorly distorting.

(That is with the crossover in stereo mode)And I had to set my amp only on HPF setting istead of low or full range because the clipping got even worse on the LPF and Full settings.  If I turn the crossover to MONO then the subs are dead quiet and I have to crank the gain on the amp up and the sub level on the crossover way up just to hear it. But the second I get it even to an audible range it clips again.

I do not understand what is going on.

I used to run the amp and sub setup off a pioneer aftermarket head unit and they worked great. I even kept the gain on the amp all the way up and had no clipping problems what so ever, so I am utterly at a loss here.

Do you possile know what I might be doing wrong? Any information would be helpful and greatly appreciated.

The Remnant

Do you have a bose system in the Tahoe? What speaker wires do you have hooked up to the crossover? (colors) My guess with the info you gave is this: bose system in the truck. There is a stock amplifier powering the stock speakers and you are getting too high of an input into the crossover Also I want you to check you wiring that you have to make sure you have the right speaker wires and polarity of those wires hooked up.