Have harman kardon avr210 home theater system. About two yrs old. Recenttly started getting a low buzz from all five speakers. Disconnected all sources (dvd, cable) still buzz. Changes slightly with vol control. Changes slightly with all surround sound settings. Changes slightly with source changes. Never stops while power is on
Audio Players & Recorders - Harman Kardon - AVR 110 Receiver
Answers & Comments
If the buzz persists when all sources are disconnected, the noise is getting into your system through the power supply. The filters in the units power regulators may be failing and require service/replacement, or something very 'noisy' in your home or neighborhood's power grid has been introduced.
Try unplugging everything except your amp from its outlet and check for the buzz. Try running extension cords from different outlets to your AV receiver, and see if using a different outlet gives a different outcome.
Ultimately, you don't want to live with extension cords I know, so the best solution I have for you is to go to a Future Shop or The Source boxing day sale today and buy the best power filter for home theaters you can afford and try it out. I have a Monster Power Reference RTS 1600 and am very happy with it. If the filter doesn't fix your problem, return it for your money back in a few days and take your amp in for servicing.
I hope that helps.