99 Alero CD/radio/speakers; looking for some info

I have the two rear 6x9s out of my old '99 Alero, and I put them in my new truck... I have a Pioneer CD player, and they don't hit near as hard as they did with the Alero CD player, so I was just wondering if there is some resistance difference or anything like the Bose systems use.

At maybe 3/8 volume, they burp/fart worse than the stock speakers up front in my S10. Is there anything I can do to fix that? Also, I turned the CD player up to maybe 1/2 volume and I blew the ground fuse that was already wired into the harness (had a Jensen tape deck in it when I bought it). TIA.