6x9s are are physically larger than most of us use. Not being round they won't as easily fit in as many containers, but surely could be made to work anyway. Evidently weight must not be much of a consideration for you. That being the case, you might want to put them in the molded enclosures that already have the 6x9 cutouts; these can sometimes find in an auto parts store. These enclosed speakers would likely provide excellent sound, even if they do weigh only slightly less than a baby pachyderm.
If you are going to use a 10 amp 12v power source, shop around for a 12v automotive stereo amp of 40A or so. (Nahuatl uses a PA horn with a mono amp from TOA that might also work). As for heat isssues any of these are bound have a heat sink already, but you might just want to allow for some ventilation holes in whatever box you put it all inside.
And yes, the amp will power the speaker(s).
LionHo
