I know with amps, 100% efficiency is king. My amp, which states 150wx2 at 2 ohms, and the two speakers, each rated 150w rms that this amp is connected to, are not very loud, but the amp gets pretty warm, almost hot. If I turn the gain down a bit, the amp will be cooler but the sound is very low to the point where my rear oem speakers running straight off the 60wx4 hu overpower the front speakers' sound... How can my two rear speakers that are hugely underpowered when compared to my two front speakers that are being fed 150w apiece overpower them? And, just to even the sound beween front and rear, I must turn the gain on the amp up to the point where it gets really warm...is this natural? it is a ppi amp.
Your fronts don't get loud enough because you're not driving your amp sufficiently.
When you turn the INPUT SENSITIVITY down, you are doing just that. It will require more voltage from the HU in the waveform to achieve maximum output.
Amps are inefficient devices. A class AB amp (typical for most full range amps) is ~63% efficient. The other remaining 37% get dissipated as heat and other losses (beyond the scope of this thread).
If the amp has a fan, when it gets too hot, the fan will turn on. Amp with no fans typically have other thermal protection, and will typically shut off after a particular thermal threshold is reached.
you're using a class AB amplifier. it's only about 50% efficient. It's going to get hot.. amplifiers always do.
set the gain appropriately for your line voltage instead of dinking with the setting like a volume knob. that's a great way to damage teh amplifier and the speakers.