Car Deck to Speaker Compatibility?

[BishopMR2]

I recently bought a set of 2 alpine speakers to replace my stock rear speakers. When I hooked them up to my pioneer premier deck, I noticed that they sound a lot worse than when I hook them up to my friends alpine deck. Both of the decks are roughly the same price (the pioneer being a little more expensive). Is this a problem of brand name compatibility or what? All the cables and everything were the same, no stock or otherwise amps on either car. Should I be buying pioneer speakers to go with a pioneer deck?

Any ideas?

[curtis20]

i have alpine 6x9 hooked up to a pioneer premier too and with out the subs on they dont sound very good but i dont have aftermarket wires for the speakers either so that might be your problem too?