get rid of the tone controlls.
and post pictures of the actual circuit built.
prehaps grounding issues, re-routing /planning grounding scheme to star ground would make improvment.
a ceramic cap from pin 11 to gnd might allso helps.
220 to 330 pf value.
I can't find a datasheet for that chipamp. Also I wonder why although there are two zobel networks shown, only one is connected to a speaker output. Is there a missing connection to that on the schematic?