Is the buzz present when no music is playing? I'm assuming you've put your ear close to the speaker drivers to make sure that is where the noise is coming from. It'd probably help to identify if it is a high frequency buzz from the tweeter or a lower buzz or hum from the woofer. If so, then the amp, preamp or source electronics are likely picking up interference somewhere. Could be anything from a light dimmer on the same circuit, an RFI source or similar. First see if the buzz disappears/reappears when various electronic and electrical items in the home are switched off and on.
If the buzz only accompanies music and gets worse with bass heavy passages, then something in or near the speakers is rattling when it shouldn't. It is likely not the speakers themselves since it is not common for two speakers to go bad in the same fashion at once. Again, find something that generates the buzz and start nosing around.
If the buzz only accompanies music and gets worse with bass heavy passages, then something in or near the speakers is rattling when it shouldn't. It is likely not the speakers themselves since it is not common for two speakers to go bad in the same fashion at once. Again, find something that generates the buzz and start nosing around.