Audio Systems: Low Sound on Two Front Speakers

Question
QUESTION: I just installed a Pioneer DEH-150MP head unit in my 1999 Honda Accord and now my front two speakers don't work properly. When I put balance all the way to the front, I can hear slight sound coming out of the speakers; but when the balance is on center, the back two speakers way overpower the front.
I double-checked the stereo’s wiring for the two front speakers and they appear to have a good connection. I also put back in the factory stereo and the speakers worked fine, so I know they're not blown out.
I think everything is factory equipment except for the front two Boss speakers which must have been installed by the previous owner. Could it be my amp is incompatible or not powerful enough for the aftermarket stereo?

ANSWER: my amp is incompatible  ? what amp you have ?
also is the factory radio Bose ?

---------- FOLLOW-UP ----------

QUESTION: The factory stereo is not Bose.

Not sure if it helps, but my model has 6-speakers, two tweeters in the dash that don't produce any sound either with the new head unit.

Also, I read that there's no amp in this model, that the speakers are powered by the factory head unit. Not sure if this is true, although I didn't find one behind the glove box.

Answer
In that case check the speaker make sure that any of the wires for the front speakers are not touching ground,
also not a bad idea to replace them they are junk,

if the speakers touch ground it will damage the pioneer radio, not the factory the outputs on this radios are not the same Honda use common ground

pioneer don't like to see ground on the speaker wires

good luck