does the actual weight of the amp makes a difference in quality. I've heard that heavy amps are better than lighter ones. EX. two 800 watt amps and one is significantly lighter than the other. I sthe heavy one better?
depends what they are made of, just because an amp is heavier doesn't neccassarly mean its better, for ex. if an amp is made of steel, it will got hot a lot faster than an amp made of aluminum or copper, because steel conducts more heat, so weight doesn't make the amp, it really depends on the company and your set-up!
Yeah, a lot are made with aluminum, some with other metals, some are even plastic. The quality of the amp is determined by the quality of internal components, a solid mounting of those components, and also the heat dissipation design. Heat is the #1 killer of electronic components.