one amp smoked, new amp cuts out and rest

Well everything comes into play here

The quality of your installs( Did you run all your wires properly thru the firewall with a grommet of thru factory rubber where there is no chance of the wire shorting to metal? or did you run the power wire thru the door jam? Are you using the proper size wire for both power and groung connections? Did you upgrade your factory ground wire between battery and frame? Are you usind the correct fuse rating? Are all off your wires properly terminated and insulted?

Is there any panels you removed to run wires and replaced with screws? Is there any chance you could have driven a screw or clip into your wires and shorted them out?

Are your amps securely and properly mounted?

Is any of your equipment exposed to moisture or excessive heat(ie; bad trunk gasket that might leak)

Are you exceeding the Ohm load capacity of your amplifier?

Lets start with these questions before we go further. I am thinking your issues are related to one or more of the questions I asked you.

For future reference. If you ever have an amplifier that FRIES do not replace with new one with replacing your Power wires. Never us used wire. Like if you get a new car and want to install your old equipment then make sure you buy a new amp kit

Good luck! Don

Fuses pop for a reason, never ever replace a fuse without finding the cause of it or you can almost guarantee magic smoke.

The big thing I see here is simple. It is hot out, ac or not. Your amp is a class AB design, it is going to get hot, it is designed to get hot. What makes matters worse is how you are using the amp. The big parts of your quote above that are smacking you upside the head and saying "dude wth" is "tunes were cranked" and "three hours".

The problem here is that the longer something is used, the more heat that builds up. The louder something is played, the more the heat that builds up. Your amp is having the equivalent of a thermal heart attack. Your combination of playing for 3 hours + cranked is going to spell SMOKE again in the future. An amp must be allowed to cool. If the amp gets too hot the thermal shutdown is going to engage as it did in your case that you mentioned in the 3 hour time frame. Ensure that you have a above average ground, this does not mean to the closest amount of sheet metal with no paint on it, it means go and find the what is a proper ground sticky and follow through on it. Ensure that your amp has the right guage of power and ground wire for the application before you cause it to have a heart attack.

A bad speaker or speakers is another possibility, all that power for that period of time may also have killed Kenny (Kenny being your speakers). If you have a speaker that plays fine at lower volume but all of a sudden sounds like a dead cat getting nailed by a Kangaroo at top volume, the speaker will cause the amp to do all sorts of wierd things. A speaker and an amp must be allowed to cool. DO NOT play them for extended periods of time without allowing them to cool, never mind the damage that your ears are receiving. A sub pounding away is going to mask the distortion coming out of the other sets of speakers. Play the system one day without your sub running so that you can accurately listen to the other speakers to see what is going on with them. Play all sorts of different music the same way you play it now, just no sub.

If long and loud is what you are indeed after, a full range class D amp for the front and rear speakers is going to be in your future. Eclipse, Alpine, Pioneer, JL Audio and others all have a new generation of amplifier for this very purpose.

Dakota Digital makes temperature guages that may be used for the amplifier. For the speakers though, this is not going to be easily done as the heat that is built up is inside of the speaker itself (this is why voicecoils or voicecoil formers melt).