Need some speaker help

 Ok so my dad has some old NS-690 speakers and an old Halfer DH-200 amp and a Halfer pre-amp. We hooked it up in the living room and hooked up a turntable. The sound was ok. Then we hooked up my iPod and the sound was a lot better. Then we hooked up a Panasonic 5 disc CD player and the sound as he says was much louder then the iPod in the signal (although my iPod was max volume he says that the CD player was louder, is that true).

OK so here is the problem. I accidentally hooked up the cable from the pre amp to the amp in the Rec out instead of the output; therefore, the volume was max when it went to the speakers, I turned the whole setup off in under three seconds and my father said that I probably blew the speakers. We hooked it up properly and the speakers were making regular noises very crisp for the song no popping or nasty noises. Now here is the tricky part: If you have the pre amp and amp on (no CD player) then on the left speaker which is right next to the pre amp makes a higher pitched humming noise coming from the tweeter but not the mid or the woofer. However, the right speaker does not have this problem. I also turned down the treble from the pre amp and the humming gets quieter and then nonexistent when the treble is at its lowest. I just now listened to it at a low volume and it made a really really low hum from the mid and woofer. My question is, did i partially blow the whole speaker or if it is just interference from the cords, and if so, is it repairable or is the speaker gone? 

Also, if it is repairable, will it cost more than just buying a new one or a new set?

If you need more details let me know!

Please do not start the same topic in multiple areas. One thread per topic. I'm closing this one in favor of the identical topic in the Speakers area:

http://www.hometheaterforum.com/forum/thread/292247/speaker-issues