I've been having this same issue as the rest with audio quality sounding like blown speakers on the 9102R streambar. Multiple channels, before and after restarting and after a factory reset. Nothing resolved the issue. Device purchased earlier this year.
I suggest you contact Roku customer service to request that they ship you a replacement Streambar. I received my replacement yesterday. It sounds good, no crackling and buzzing, at least the 1st day of use.