Manu:
You cannot damage a AVR by setting the output level of a channel high. The AVR does not do anything but send data out. There is no feedback for the AVR to get spoiled.
It looks likes either the amplifier or the driver of your sub has got spoiled. Please ask the dealer you bought it from to check the sub. He may need to change a capacitor o something in the amplifier. Let us pray the driver is safe.
Cheers
Subash:
I have listened to a large number of varied system including Parasound, Onkyo, Denon, Yamaha, Arcam, driving speakers from Wharfedale, B&W, PSB, QA, etc. I have also seen Blu-Ray source systems driving FullHD projectors from companies such as Optoma, Runco, and Meridian.
Sometime ago when I was in Delhi, Sound of Music demonstrated the Meridian systems quite extensively to me. They were driving the Meridian through both Meridian speakers and through Avant Garde Horn speakers, and , they were driving them at INSANE levels to demonstrate lack of distortion even at around 110db. Believe me, if you sit through a movie at those levels, you are only hurting yourself. I recently saw a Blu-Ray version of Dark Night and I was very happy at around 70dB. I could hear all the dialogues properly as well as the surrounding noises and music extremely well. That is all I want. I don't know about others, but for me background music is always at around 30 dB, never more. When I sit and listen to music specifically I may up the volume to around 60dB. Many times I have walked out of cinema halls as they were playing at uncomfortable volumes. Only last week, in a music session, I insisted that the volume be reduced as the sound was hurting. The sound engineer would not believe me till I made him come down and sit in my seat. He immediately rushed and cut the volume.
It is not that I don't know what I am missing. Some of the music I use for auditioning I know very intimately as I have heard them innumerable times using headphones.
But those are my tastes. I am sure others would have different tastes. Yet, please remember that the human ear cannot sustain a continuous barrage of sound at more than 75dB. If that is done, you are slowly going deaf.
Cheers