What causes "crackling noise" from "A" side banana plug output? I've replaced the banana plug and cable.

With nothing plugged in and the noise still there it most likely the output stage of the amp. If the unit is under warranty - tag it, bag it, and send it back for a new one. If not under warranty, you should remove the chassis and inspect for anything loose and spray the guts with zero residue contact cleaner. Use the cleaner liberally. Usually these output noises are the result of loose or dirty components. Clean all the electronics, put it back together and see if that doesn't get rid of the noise.
Good Luck!
Chad

how about the speaker did you tried to check weather the cone get worn out so it has crackling sounds.

The audio output section circuit has the fault. Check and replace audio output circuit board as card basis.

I just repaired an Adam A8X which had intermittent noise coming from the woofer. Turns out it has two (cheap?) volume knobs inside for factory calibration, which are not accessible to the user. In my case the low-frequency pot had collected dust and caused intermittent noise and reduced woofer output. I opened the unit up, rotated the knobs back and forth a little bit and set them back to their original position. This resolved it. Maybe your issue is related. They may have fixed this in MK2?

Allan, It sounds like you have what is called a ground loop. A ground loop can occur when two pieces of equipment are connected together through a home or buildings safety ground through the same power source. For instance, your PC is connected to a power source through the AC adapter or plug, and your external powered speakers are receiving power from the same power source. The surrounding cables as well as the AC adapter(s) can act like an antenna. This will cause a low hum or crackling that would be audible through the speakers or headphones.

You may want to try plugging all components into a power strip so they are all on the same circuit. You may also want to be sure that the AC adapter cables are not not laying or running across other electrical components plugged into a different socket.

If you get the same hum through your headphones check to see if the headphones were manufactured with shielded cabling. A shielded cable is made with a wire mesh around the outside that helps reduce electrical noise. Hope this helps a little. Thanks!

The crackling (which sounded a little like a geiger counter) which I could hear when the oven was NOT running was coming from the speaker (where the beeps come from). I unplugged the oven, found the little speaker on the circuit board, yanked one of the wires off of it, and the crackling was be gone.

I have the same tuner with the same problem. I have 2 pairs of Bose Acoustimas speakers and a pair of their sub woofers. I found it was the vibration from the subwoofers were causing so much vibration even using monster wire the crackling was caused by wire vibration at the speaker or subwoofer. if you are using twisted wire with a banana plug on the end or straight twisted wire into the speakers the constant vibrartion eats into the wire. Just pull the wires out re twist or tin (solder) the tips or move to a different location on the banana plug and really twist it will getting a bite into the wire. If you are using straight banana plugs use a screwdriver in the 4 slots to make them fatterso they stay tight. if they are RCA jacks pinch down the 4 outside tabs so they grip harder. Viva La France.

crackling noise or really bad distortion check wires and if blown send it to alpine

Is it an input cable or output cable?

Do you have another one you could swap out?

could be one of the internal wires is loose, possibly where it connects to the back side of input jack.