hardware problem (?) with speakers

5.1 Edifier s550

My speakers began to crackle, and after a few days of trying to diagnose the problem, dust accumulation in the speaker's ports turned out to be causing the sound. Blew it out. Good as new.

It returned later that week (it seems apparent that my place needs a serious dusting). Blew on the ports again, crackling went away.

Now it seems clear to me that the crackling was a multi-cause problem. Even after dusting the ports the crackling returns once the speakers are given input. IE, with power on and the speakers being powered there is no crackling whatsoever, but once I plug in the RCA into the FL, FR, SL, SR, C and Sub ports the crackling returns.

So I tried blowing on the inputs. No dice.

I doubt the onboard audio is faulty, but I'll keep trying different things to narrow down the suspects like a game of clue. Any help on this would be appreciated.

A) The speakers are not faulty, however
B) The amplifier/sub's internal card could be, and
C) Once input is given, speakers begin to crackle.

Also: My living room is laminate, not carpeted, which means dust swirls around like a desert and accumulates. Easy to clean, but the dust is never trapped in the fibres of a carpet. What steps can I take to reduce the amount of dust whirling about around the amplifier without taking away sound quality?

It either comes from all or none. If one speaker is crackling, they all are, often uniformly, but not always.

I've only used the cables that came with the system, and there is a 2.1 auxiliary input.

I have also not observed crackling from other speakers, but I still denote the notion that the speakers themselves are faulty.

I can certainly try, but the crackling isn't consistent enough to do this quick.

Update: I've observed this before, but plugging the 3.5mm jack for the front speakers into the case's front port instead of the back panel doesn't eliminate the crackling, but significantly reduces it.

Earlier I was observing some minor occasional crackling, but halfway through a movie it stopped. Hasn't happened in about 3 hours.

Update: No crackling has been observed for about 18 hours. Now I just heard my neighbours kids come in (I live in a duplex) and suddenly my speakers begin to crackle. This might have something to do with poor wiring in the house. Something my neighbours kids are doing could be making my speakers crackle. Turning something on or off. I noticed with my last set of speakers that whenever the fan in the downstairs bathroom was turned on or off the speakers would give off a loud pop sound.