Oynko CR-725DAB problem, not sure what it is.

I've had my little Onkyo CR-725DAB for a few year now & it's been problem free until recently.

So i'm wondering if anybody can help.

Basically what happening is that their seems to be a slight crackle & what sounds like hissing/ interference coming though the left speaker, sometime it happen on the right speaker aswell, which also causing the music to drop out slightly.

Now i've checked all the wirining including resoldered the banana plugs on the speaker cable, but hasn't cure the problem.

I'm beginning to think it's proberly time for a new system, unless somebody has an idea what could be causing this problem.