Denon avc-3020 amplifier, both rear speakers play the same sound, sounds from the left also play through the right rear speaker and vice versa

Determining the Cause of the Problem Let's assume our system has a head unit, a crossover, a two channel amplifier and two door speakers with only the right speaker working (the left speaker is not working). If the door speakers are behind the door panels then we want to make sure the speaker is the problem before removing the panel. We'll work backwards starting with the amplifier and ending at the head unit. Testing for a Speaker Problem With the vehicle and the stereo turned off disconnect the speaker wires for both the left and right speakers at the amplifier. Now connect the left speaker to the right amplifier output (which we know works). Turn on the stereo system and make sure the balance is set to the middle position.If the speaker still doesn't work then the problem is somewhere between the amplifier and the speaker Testing for an Amplifier Problem Now we'll need to see if the amplifier channel is bad. Put the left speaker back on the left amplifier channel and the right speaker on the right amplifier channel. This returns the speaker wiring to its original configuration. Again, with the vehicle and stereo off unplug the RCA cables from the amplifier's input and switch them so the left cable is in the right input and vice versa. Turn on the stereo system. Testing for an RCA Cable Problem For any intermediate components between the amplifier and the head unit follow these steps for each one. We only have a crossover so we'll just do this once. Begin by testing the RCA cables between the intermediate component and the amplifier. Unplug both RCA cables from the intermediate component's output. Now plug the working channel's RCA cable into the non-working side of the crossover. In our case the working channel is the right so plug the right RCA cable from the amplifier into the left side of the crossover. Turn on the stereo system.
If the right channel continues to work then you know the problem is in the RCA cables between the amp and the crossover. esting for a Crossover or Equalizer Problem At the input of the intermediate component (in our case the crossover) flip the RCA cables around (left to right input and vice versa). Turn on the stereo system.
If the right channel continues to work and the left channel continues to not work then you know the problem is in the intermediate component. Replace or repair this component.
If the problem is now in the right speaker and the left speaker works then the problem lies before the crossover. Turn off the stereo system and return the RCA cables to their normal places.
Testing for a Head Unit or RCA Cable Problem Pull out the head unit from the dash so you can access the RCA cables. Unplug both RCA cables from the head unit. Do not disconnect any other wiring. Plug the right RCA cable into the left channel of the head unit. Turn on the stereo system.

Are you sure you wired up the head unit correctly? It is fairly uncommon for a audio output amplifier to blow out leaving 3 working speakers and 1 not working. So more than likely it is bad wiring or a blown speaker. Best bet would be get a digital multimeter and ohm out the speaker and see if it has continuity and is the same as the adjacent speaker. You could also try swapping the left/right channel wiring and see if the front right speaker stops working when connected to the left speaker output or vice versa.

Is the sound on both channels on a pair of headphones? If it is suspect a faulty headphone socket, especially if the speakers are cut out when the headphone jack is inserted - normally.

So you want to slave the 3020 to the 1082, right? Use the Pre-outs on the AVR to feed the amp. I imagine the AVR manual, which I cannot find, talks about that.

Nothing should be connected to PHONO except a turntable.

Reverse the leads left-to-right and see where that takes you for the root. Might be a bad cable.

This is likely due to a problem with the amplifier. You may have turned up the amp to the point of overdriving the speaker. The distortion at these high levels cause clipping and turn what was once crisp, clear sound into a muddied, garbled mess.

If the speaker is left connected to that source long enough, damage to the speaker and the amp may occur.

Without changing positions of the speakers: You can disconnect the affect Front or Rear L & R speakers and swap them (connect the L speaker to the R output of the amp and vice-versa). If the buzzing / hum "moves" to the other speaker, then the amplifier has the problem. If the buzzing / hum stays with the same speaker, the speaker has issues and is likely "blown".

Either way, it is probably not going to be a "cheap fix"

Good luck!

hmmm. Let's start by swapping the wires you are using for your speakers. Double check the wire connections first, then take the left and place iton the right and vice versa.

I have similar issue with my 3020...I may break down and buy the service manual.

volume levels on all channels varies depending on what dsp mode you are using. to be able to determine the level you desire, just chnge the level setting of those channels. either you do it by remote control or the front panel of the amp. try setting the dsp mode on disco and you should hear higher vol levels on all channels. Do not expect as well all channels to produce same vol levels as your effects speakers may not be able handle higher power levels.

1-check sound input source(dvd -tuner-deck)and confirm that amplifier is assigned to sound source-you must check source with it is cabels.
2-check sound output with it is cabels(speakers).
3-if every thing is fine your amp has a problem and needs to go to service center.