Amp stopped working

It sounds like a defective/incorrect AC-to-DC adapter may have caused your problem. These adapter come with different output voltages, AC or DC output and different amperage ratings. AC-to-DC adapters list the polarity of the DC voltage as it relates to the DC power plug and you must match both the devices voltage and power requirements. As for the amp...not working on batteries either, I would suspect output transistors or IC.

Not true! CD channels don't require a pre-amp and the cartridge for a turntable does. I suspect that when the power went off the mixer was still on, so that when power was restored it came back on. However this resulted in a surge inside the unit. Magnetic cartridge pre-amps are often very sensitive to this kind of thing and will sometimes fail, while everything else works fine. This would result in no sound from the record decks, but sound from CD players etc.

What is the make and model, it sounds like its going into overload protection, if the speakers aren't hooked up you have some bad components in the output section.

Sounds like an amp issue. Does the ohms reading of the sub match the amp? typically this is what kills amps.

My best guess is that it would be your ground wire or even the power into your amp. I would check all the connections going to and from your amp

Not a fuse. First thing, to check your speaker (amp unplugged, of course), touch the + and - speaker connections to a 9V battery. If you don't hear a pop sound then your speaker is blown. Thus, no output sound. If speaker is OK, then the output IC is your problem.

i had an amp that did that for a while before frying. its possible that it could be overheating causing it to go into protection mode which can be fixed with a cooling fan or remounting it somewhere else so it can get some air. it needs to be mounted in a way that it will have at least 1/2" clearance under it so it can have plenty of airflow. the other thing is you may be putting too much of a load on the amp causing it to go to protection mode. check and see how u have the sub wired and if the amp is stable. if u have the sub wired at 2ohm for more power output and the amp is only stable at 4ohm, then the amp will overload and cause the problem your experiencing. thats what happened to my amp. i had it wired for more than it was stable for and it fried

Most of these problems are rooted in a failed power amp module.
I'm working on an older technics unit but with the same troubles.

Ok This is a two channel High Current amp. It is stable to one ohm. If the Subs are single voice coil at two ohms the they have to be wired in Parallel that means (Red +) (Black -) are connected to the + and - of another sub and then the (RED +) (Black -) from both go to one output channel of the amp. You pair the other two in the same fashion on the other output channel. If you are getting no output (sound) at all first check if the amplifier is going into protect. (Usually indicated by a red led on the unit. If it is connect only one Sub to each output and see if the protect LED goes out. If it does then you should have sound at the subs. If not check that you have the sub output enabled on the HU some head units do not come with the sub output enabled on the HU. If every thig is enabled, with only one sub connected to each output and the protect LED is not on then your amp is probably blown and needs repair. Nice thing is that MA has a great warrenty policy. Check and make sure the protect LED is off. If it is on you probably have the SUBS wired wrong

This is not a problem that a normal comsumer should try to repair themselves. It's time to take it to a pro. It sounds like you have blown out at least one of your output channels. If you are getting any red light at all then the good news is that the power supply section of the amp is probably still good. About half of all the electronics in your amp is for the power supply section. The other half is for the actual amplifiers of the amp. Good luck, I hope it's not too bad.