The speakers on my kn6000 are 'crackling' and 'rattling' making it unusable except through a PA system ... are there certain speakers that have to be used as replacements, or can 'similar' speakers be used, and is this something I could do, or is a professional technician necessary?
thank you,

Hi Tony, I had a fault close to your as my keyboard had been gigged bits of fine rubbish had entered the case via the gaps in between the keys and around the speaker grills etc. I just took off the top cover and used an air duster held about 10/12" from the speaker to gently remove the rubbish (don't hit the speaker cone square on as this may cause damage try to aim at an angle causing the air to glance off thus removing dirt without damage to the speaker cone material) if this fails to solve the problem speaker replacement is the next step if the speaker wires are soldered make sure you mark the wires one will be connected to a marked terminal( a dot or different size connector ,if don't reconnect you can end up with the speakers out of phase.
For replacement the speakers will be marked and if you are close to a good electronics suppliers they should be able to match your samples,also if you are replacing one always replace in pairs to ensure correct balance in output and voicing.
Hope this helps and good luck regards John.