Do you also have a Sub paired with the Beam? If not, what level do you have the bass set at in the EQ settings?

No sub. I have a pair of Play 5 but not connected to the TV. Equalizer settlngs are kept neutral (standard) The problem is a “tinny” og metallic sound and comes from both streaming radio directly and from any source on the tv (streaming or cable). 

There was an update that was releases today that may help. Try that to see if it changes anything. 

If it doesn't improve the audio quality, I would suggest getting in touch with Sonos support. They have the tools to diagnose if there is a hardware, software or network issue.

Using a paper towel tube, listen to each of BEAM’s speakers for the buzzes. This will be easier if you use test tones. Tones are available from many sources, the Bink Audio Test CD is one source.

Mechanical issues with a speaker driver are usually restricted to a certain (narrow) frequency range. Electronic problems with frequencies assigned to that driver will tend to be constant amplitude over the range. I wish I could be more specific, but this call requires some experience.