Help - Paradigm pw2200 subwoofer interfering with sound

MAD

A paradigm pw2200 V2 class D subwoofer came up for sale, I raced out with my ipod and y cable, plugged it directly into the back of the sub and gave it a listen. It sounded great in my mind (a good combination of chest hit along with a touch of boom, but not too much).
I bought it.

I get home, split the pre out from my pre amp, and hook it up.
The sub sounds great, compliments the sda 2.3 very well but I can now hear background noise through my speakers and they are not as clear and sometimes it distorts the treble.

Then I tried to hook it up a different way.
The sub does not have speaker level ins, so I used an old external crossover from energy that converts the speaker level to rca and plugged that into the sub.
I still hear feedback from the speakers, the noise floor increased.

With the sub unplugged it seems to go back to normal.
Do you think it is a ground loop issue?
I have never had any of this with any other sub in the exact same setup.

The problem is I really love the combination with this subwoofer.

Any advice or tests?

Thanks in advance,

Mike

ALSATIAN in USA

also, he boost at 8db - 24HZ, that's why he sound good!... Your external X-Over is a pro-stuff??? if yes, you have to (unground) your X-Over with a (3 to 2) prong (it's mostly gray and you found that at WALMART for $3)