[Mjulnir]

I used a pair of Sony 6" car speaker for a long time with a cheap Yamaha RXV with no issues about heat etc. They sounded terrible in drywall (no surprise). as the back of the wall was the garage I ripped a hole in it and reinforced the drywall around the speaker with plywood and filled it with insulation. This helped but when I used a similar pair for downstairs I used boxes (about 1^3 ft).