’05 tahoe stock stereo w/aftermarket amp

I checked the low pass xover so did the guy who sold me the hi/lo converter.  All seems ok.  I should have made them replace the hi/lo converter because that's the only new thing in the mix but they didn't seem to want to admit that it was the problem and I was sick of dealing with them by then.  It's a simple straight forward installation.  It should work.  As for the rear speakers, they are still working.  I just tapped into the wires.  When I look at the meter on my amp  there's barely any movement.  I'll probably trash the converter.

Ok, I'm back.  I installed the electronic xover.  The output is a little better but only a little.  I replaced the old hi/lo converter with a new one.  Everything works but the output is really low as if there's not enough signal getting to the amp.  I'm still using the same amp and subs I used on the other vehicle.  The only difference is I had to hook it up using the hi/lo and xover (using stock radio) instead of rca's from aftermarket head unit.  Please help.

Alex.